In each of the following, find the equation of the circle with
Centre (0,2) and radius 2
The equation of a circle with centre (h,k)
and radius r is given as (x-h)2+(y-k)2=r2
It is given that centre (h,k)=(0, 2) and radius (r)=2.
Therefore, the equation of the circle is
(x-0)2+(y-2)2=22
⇒ x2+y2+4-4y=4
⇒ x2+y2 -4y=0
Therefore, the equation of the circle is x2+y2 -4y=0
In each of the following, find the equation of the circle with
Centre (–2,3) and radius 4
The equation of a circle with centre (h,k) and radius r is given as
(x-h)2 + (y-k)2=r2
It is given that centre (h,K) = (-2,3) and radius (r) =4
Therefore, the equation of the circle is
(x+2)2 + (y-3)2 = (4)2
⇒ x2 + 4x + 4 + y2 - 6y + 9 = 16
⇒ x2 + y2 + 4x - 6y - 3 = 0
Therefore, the equation of the circle is x2 + y2 + 4x - 6y - 3 = 0
In each of the following, find the equation of the circle with
Centre () and radius (1/12)
The equation of a circle with centre (h,k) and radius r is given as
(x-h)2 + (y-k)2=r2
It is given that centre (h,k)= and radius(r) = .
Therefore, the equation of the circle is
⇒ x2 – x + + y2 -
⇒ x2 – x + + y2 -
⇒ x2 – x + + y2 -=0
⇒ 144x2 -144x + 36 + 144y2 -72y + 9- 1=0
⇒ 144x2 -144x+ 144y2 – 72y + 44 =0
⇒ 36x2 +36x+ 36y2 -18y+11 = 0
⇒ 36x2 +36y2 -36x – 18y+ 11= 0
In each of the following, find the equation of the circle with
Centre (1,1) and radius
The equation of a circle with centre (h,k) and radius r is given as
(x-h)2 + (y-k)2=r2
It is given that centre (h,k) =(1, 1) and radius (r) =.
Therefore, the equation of the circle is
(x-1)2 + (y-1)2=
⇒ x2 – 2x + 1 + y2 -2y + 1 =2
⇒ 2 + y2 -2x -2y=0
In each of the following, find the equation of the circle with
Centre (–a, –b) and radius .
The equation of a circle with centre (h,k) and radius r is given as
(x-h)2 + (y-k)2=r2
It is given that centre (h,k) = (-a, -b) and radius (r) =
(x + a)2 +(y + b)2 =
⇒ x2 + 2ax + a2 + y2 + 2by + b2 = a2 – b2
⇒ x2 + y2 +2ax + 2by + 2b2 = 0
In each of the following, find the centre and radius of the circles.
(x + 5)2 + (y – 3)2 = 36
The equation of the given circle is (x+5)2 +(y-3)2 = 36.
(x+5)2 +(y-3)2 = 36
+ (y - 3)2 =62, which is of the form (x – h)2 + (y – k )2 = r2,
Where, h =-5, k =3 and r= 6.
Thus, the centre of the given circle is (-5, 3), while its radius is 6.
In each of the following, find the centre and radius of the circles.
x2 + y2 – 4x – 8y – 45 = 0
The equation of the given circle is x2 + y2 – 4x – 8y – 45 = 0.
x2 + y2 – 4x – 8y – 45 = 0
(x2 – 4x) + (y2 -8y) =45
+ – 4 – 16 = 45
(x - 2)2 + (y – 4)2 =65
(x - 2)2 + (y – 4)2 =, which is form (x-h)2 +(y-k)2 = r2, where h=2,
K= 4 and r=
Thus, the centre of the given circle is (2, 4), while its radius is.
In each of the following, find the centre and radius of the circles.
x2 + y2 – 8x + 10y – 12 = 0
The equation of the given circle is x2 + y2 -8x + 10y -12 =0.
x2 + y2 -8x + 10y -12 =0
(x2 – 8x) + (y2+10y) = 12
+ – 16 – 25 = 12
(x - 4)2 + (y + 5)2 =53
(x - 4)2 + =, which is form (x-h)2 +(y-k)2 = r2, where h=4,
K= -5 and r=
In each of the following, find the centre and radius of the circles.
The equation of the given of the circle 2x2 + 2y2 –x =0.
2x2 + 2y2 –x =0
(2x2 + x) +2y2 =0
+ y2 - = 0
+ (y - 0)2 = , which is of the form (x-h)2 + (y-k)2 =r2,
Where, h = , k = 0, and r=
Thus, the centre of the given circle is , while its radius is .
Find the equation of the circle passing through the points (4,1) and (6,5) and whose centre is on the line 4x + y = 16.
Let the equation of the required circle be (x – h)2+ (y – k)2 =r2
Since, the circle passes through points (4,1) and (6,5),
(4 – h)2+ (1 – k)2 =r2 .................(1)
(6– h)2+ (5 – k)2 =r2 ..................(2)
Since, the centre (h,k) of the circle lies on line 4x+y = 16,
4h + k =16..................... (3)
From the equation (1) and (2), we obtain
(4 – h)2+ (1 – k)2 =(6 – h)2 + (5 – k)2
16 – 8h + h2 +1 -2k +k2 = 36 -12h +h2+15 – 10k + k2
16 – 8h +1 -2k + 12h -25 -10k
4h +8k = 44
h + 2k =11................ (4)
On solving equations (3) and (4), we obtain h=3 and k= 4.
On substituting the values of h and k in equation (1), we obtain
(4 – 3)2+ (1 – 4)2 =r2
(1)2 + (-3)2 = r2
1+9 = r2
r =
Thus, the equation of the requires circle is
(x – 3)2+ (y – 4)2 =
⇒ x2 -6x + 9 + y2 – 8y + 16 =10
⇒ x2 + y2 -6x – 8y = 15 =0
Find the equation of the circle passing through the points (2,3) and (–1,1) and whose centre is on the line x – 3y – 11 = 0.
Let the equation of the required circle be (x – h)2+ (y – k)2 =r2
Since, the circle passes through points (2,3) and (-1,1).
(2 – h)2+ (3 – k)2 =r2 .................(1)
(-1 – h)2+ (1– k)2 =r2 ..................(2)
Since, the centre (h,k) of the circle lies on line x - 3y - 11= 0,
h - 3k =11..................... (3)
From the equation (1) and (2), we obtain
(2 – h)2+ (3 – k)2 =(-1 – h)2 + (1 – k)2
⇒ 4 – 4h + h2 +9 -6k +k2 = 1 + 2h +h2+1 – 2k + k2
⇒ 4 – 4h +9 -6k = 1 + 2h + 1 -2k
⇒ 6h + 4k =11................ (4)
Now multiply (3) by 6 and subtract it from (4) to get,
6h+ 4k - 6(h-3k) = 11 – 66
⇒ 6h + 4k – 6h + 18k = 11 – 66
⇒ 22 k = - 55
⇒ K = -5/2
Put this value in (4) to get,
6h + 4(-5/2) = 11
⇒ 6h – 10 = 11
⇒ 6h = 21
⇒ h = 21/6
⇒ h = 7/2
Thus we obtain h= and k= .
On substituting the values of h and k in equation (1), we get
+= r2
+= r2
+ = r2
+ = r2
Thus, the equation of the required circle is
+=
+=
⇒ 4x2 -28x + 49 +4y2 + 20y + 25 =130
⇒ 4x2 +4y2 -28x + 20y - 56 =0
⇒ 4(x2 +y2 -7x + 5y – 14) = 0
⇒ x2+y2-7x + 5y– 14 =0
Find the equation of the circle with radius 5 whose centre lies on x-axis and passes through the point (2,3).
Let the equation of the required circle be (x – h)2+ (y – k)2 =r2
Since the radius of the circle is 5 and its centre lies on the x-axis, k= 0 and r= 5.
Now, the equation of the circle becomes (x – h)2 + y2 = 25.
It is given that the circle passes through the point (2, 3) so the point will satisfy the equation of the circle.
(2 – h)2+ 32 = 2
(2 – h)2 = 25-9
(2 – h)2 = 16
2 –h == 4
If 2-h =4, then h = -2
If 2-h = -4, then h =6.
When h= -2, the equation of the circle becomes
(x – 2)2 + y2 = 25
⇒ x2 -12x + 36 + y2 = 25
⇒ x2 + y2 -4x + 21 =0
When h= 6, the equation of the circle becomes
(x – 6)2 + y2 = 25
⇒ x2 -12x + 36 + y2 = 25
⇒ x2 + y2 -12x + 11 =0
Find the equation of the circle passing through (0,0) and making intercepts a and b on the coordinate axes.
Let the equation of the required circle be (x – h)2+ (y – k)2 =r2
Since, the circle passes through (0, 0),
(0 – h)2+ (0 – k)2 =r2
h2 + k2 = r2
The equation of the circle now becomes (x – h)2+ (y – k)2 = h2 + k2.
It is given that the circle makes intercepts a and b on the coordinate axes.
That means that the circle passes through points (a, 0) and (0,b). Therefore,
(a – h)2+ (0 – k)2 =h2 +k2.................(1)
(0 – h)2+ (b– k)2 =h2 +k2..................(2)
From equation (1), we obtain
a2 – 2ah + h2 +k2 = h2 +k2
a2 – 2ah = 0
a(a – 2h) =0
a = 0 or (a -2h) = 0
However, a 0; hence, (a -2h) = 0
h =.
From equation (2), we obtain
h2 – 2bk + k2 + b2= h2 +k2
b2 – 2bk = 0
b(b– 2k) = 0
b= 0 or (b-2k) =0
However, a 0; hence, (b -2k) = 0
k =.
+=
⇒ 4x2 -4ax + a2 +4y2 - 4by + b2 =a2 + b2
⇒ 4x2 + 4y2 -4ax – 4by =0
⇒ 4( x2 +y2 -7x + 5y – 14 ) = 0
⇒ x2+y2- ax - by=0
Find the equation of a circle with centre (2,2) and passes through the point (4,5).
The centre of the circle is given as (h,k) = (2,2).
Since, the circle passes through point (4,5), the radius (r) of the circle is the distance between the points (2,2) and (4,5).
r =
=
=
=
Thus, the equation of the circle is
(x– h)2+ (y – k)2 =r2
(x –h)2 + (y – k)2 =
(x –2)2 + (y – 2)2 =
x2 - 4x+4 +y2- 4y+4 =13
x2 +y2 – 4x -4y = 5
Does the point (–2.5, 3.5) lie inside, outside or on the circle x2 + y2 = 25?
The equation of the given circle is x2 +y2 = 25.
x2 +y2 = 25
(x– 0)2 +(y – 0)2 = 52, which is of the form (x – h)2+ (y – k)2 =r2,
Where, h=0, k=0 and r=5.
Distance between point (-2.5, 3.5) and the centre (0,0)
=
=
=
=4.3 (approx.) <5
Since, the distance between point (-2.5, -3.5) and the centre (0, 0) of the circle is less than the radius of the circle, point (-2.5, -3.5) lies inside the circle.
In each of the following, find the coordinates of the focus, axis of the parabola, the equation of the directrix and the length of the latus rectum.
y2 = 12x
The given equation is y2 = 12x
Here, the coefficient of x is positive.
Hence, the parabola opens towards the right.
On comparing this equation with y2 = 4ax, we get,
4a = 12
⇒ a = 3
Thus,
Co-ordinates of the focus = (a, 0) = (3, 0)
Since, the given equation involves y2, the axis of the parabola is the x-axis.
Equation of directrix, x =-a, then,
x + 3 = 0
Length of latus rectum = 4a = 4 × 3 = 12
In each of the following, find the coordinates of the focus, axis of the parabola, the equation of the directrix and the length of the latus rectum.
x2 = 6y
The given equation is y2 = 6y
Here, the coefficient of y is positive.
Hence, the parabola opens upwards.
On comparing this equation with y2 = 4ay, we get,
4a = 6
⇒ a =
Thus,
Co-ordinates of the focus = (0,a) =
Since, the given equation involves x2, the axis of the parabola is the y-axis.
Equation of directrix, y =-a, then,
y =
Length of latus rectum = 4a = 6
In each of the following, find the coordinates of the focus, axis of the parabola, the equation of the directrix and the length of the latus rectum.
y2 = – 8x
The given equation is y2 = -8x
Here, the coefficient of x is negative.
Hence, the parabola open towards the left.
On comparing this equation with y2 = -4ax, we get,
-4a = -8
⇒ a = 2
Thus,
Co-ordinates of the focus = (-a,0) = (-2, 0)
Since, the given equation involves y2, the axis of the parabola is the x-axis.
Equation of directrix, x =a, then,
y = 2
Length of latus rectum = 4a = 8
In each of the following, find the coordinates of the focus, axis of the parabola, the equation of the directrix and the length of the latus rectum.
x2 = – 16y
The given equation is x2 = -16y
Here, the coefficient of y is negative.
Hence, the parabola opens downwards.
On comparing this equation with x2 = -4ay, we get,
-4a = -16
⇒ a = 4
Thus,
Co-ordinates of the focus = (0,-a) = (0,-4)
Since, the given equation involves x2, the axis of the parabola is the y-axis.
Equation of directrix, x =a, then,
y = 4
Length of latus rectum = 4a = 16
In each of the following, find the coordinates of the focus, axis of the parabola, the equation of the directrix and the length of the latus rectum.
y2 = 10x
The given equation is y2 = 10x
Here, the coefficient of x is positive.
Hence, the parabola open towards the right.
On comparing this equation with y2 = -4ax, we get,
4a = 10
⇒ a =
Thus,
Co-ordinates of the focus = (a,0) =
Since, the given equation involves y2, the axis of the parabola is the x-axis.
Equation of directrix, x =-a, then,
x =
Length of latus rectum = 4a = 10
In each of the following, find the coordinates of the focus, axis of the parabola, the equation of the directrix and the length of the latus rectum.
x2 = – 9y
The given equation is x2 = -9y
Here, the coefficient of y is negative.
Hence, the parabola open downwards.
On comparing this equation with x2 = -4ay, we get,
-4a = -9
⇒ a =
Thus,
Co-ordinates of the focus = (0,-a) =
Since, the given equation involves x2, the axis of the parabola is the y-axis.
Equation of directrix, y = a, then,
x =
Length of latus rectum = 4a = 9
In each of the, find the equation of the parabola that satisfies the given conditions:
Focus (6,0); directrix x = – 6
Focus (6,0); directrix x = -6
Since, the focus lies on the x–axis is the axis of the parabola.
Thus,
The equation of the parabola is either of the form y2 = 4ax or y2 = -4ax.
It is also seen that the directrix, x = -6 is to the left of the y- axis, while the focus (6, 0) is to the right of the y –axis.
Hence, the parabola is of the form y2 = 4ax.
Here, a = 6
Thus, the equation of the parabola is y2 = 24x.
In each of the, find the equation of the parabola that satisfies the given conditions:
Focus (0,–3); directrix y = 3
Focus (0, -3); directrix y = 3
Since, the focus lies on the y–axis, the y-axis is the axis of the parabola.
Thus,
The equation of the parabola is either of the form x2 = 4ay or x2 = -4ay.
It is also seen that the directrix, y = 3 is above the x- axis, while the focus (0,-3) is below the x-axis.
Hence, the parabola is of the form x2 = -4ay.
Here, a = 3
Thus, the equation of the parabola is x2 = -12y.
In each of the, find the equation of the parabola that satisfies the given conditions:
Vertex (0, 0); focus (3, 0)
Vertex (0, 0); focus (3, 0)
Since, the vertex of the parabola is (0, 0) and the focus lies on the positive x-axis, x-axis is the axis of the parabola, while the equation of the parabola is of the form y2=4ax.
Since, the focus is (3, 0), a = 3
Thus, the equation of the parabola is y2 = 4 × 3 × x,
=> y2 = 12x
In each of the, find the equation of the parabola that satisfies the given conditions:
Vertex (0, 0); focus (–2, 0)
Vertex (0, 0); focus (-2, 0)
Since, the vertex of the parabola is (0, 0) and the focus lies on the positive x-axis, x-axis is the axis of the parabola, while the equation of the parabola is of the form y2=-4ax.
Since, the focus is (-2, 0), a = 2
Thus, the equation of the parabola is y2 = -4 × 2 × x,
=> y2 = -8x
In each of the, find the equation of the parabola that satisfies the given conditions:
Vertex (0, 0) passing through (2, 3) and axis is along x-axis.
Since, the vertex is (0, 0) and the axis of the parabola is the x-axis, the equation of the parabola is either of the from y2=4ax or y2 = -4ax.
The parabola passes through point (2, 3), which lies in the first quadrant.
Thus, the equation of the parabola is of the form y2 = 4ax, while point (2, 3) must satisfy the equation y2 = 4ax.
Thus,
32 = 4a(2)
⇒ a = 9/8
Thus, the equation of the parabola is
⇒ 2y2 = 9x
In each of the, find the equation of the parabola that satisfies the given conditions:
Vertex (0, 0), passing through (5, 2) and symmetric with respect to y-axis.
Since, the vertex is (0, 0) and the parabola is symmetric about the y-axis, the equation of the parabola is either of the from x2=4ay or x2 = -4ay.
The parabola passes through point (5, 2), which lies in the first quadrant.
Thus, the equation of the parabola is of the form x2 = 4ay, while point (5, 2) must satisfy the equation x2 = 4ay.
Thus,
52 = 4a(2)
⇒ 25 = 8a
⇒ a = 25/8
Thus, the equation of the parabola is
⇒ 2x2 = 25y
In each of the, find the coordinates of the foci, the vertices, the length of major axis, the minor axis, the eccentricity and the length of the latus rectum of the ellipse.
The given equation is
Here, the denominator of is greater than the denominator of .
Therefore, the major axis is along the x-axis, while the minor axis is along the y-axis.
On comparing the given equation with =1, we obtain a =6 and b =4.
Therefore,
The coordinates of the foci are (2, 0) and (-6, 0).
The coordinates of the vertices are (6, 0) and (-6, 0)
Length of major axis = 2a =12
Length of minor axis = 2b =8
Eccentricity, e
Length of latus rectum =
In each of the, find the coordinates of the foci, the vertices, the length of major axis, the minor axis, the eccentricity and the length of the latus rectum of the ellipse.
The given equation is or
Here, the denominator of is greater than the denominator of.
Therefore, the major axis is along the x-axis, while the minor axis is along the y-axis.
On comparing the given equation with , we obtain b =2 and a =5.
c = =
Therefore,
The coordinates of the foci are (0, ) and( 0, - ) .
The coordinate of the vertices are (0, 5) and (0, -5)
Length of major axis = 2a =10
Length of minor axis = 2b =4
Eccentricity, e
Length of latus rectum =
In each of the, find the coordinates of the foci, the vertices, the length of major axis, the minor axis, the eccentricity and the length of the latus rectum of the ellipse.
The given equation is =1 or =1.
Here, the denominator of is greater than the denominator of.
Therefore, the major axis is along the x-axis , while the minor axis is along the y-axis.
On comparing the given equation with =1, we obtain b =4 and a =3.
c = =
Therefore,
The coordinates of the foci are ().
The coordinate of the vertices are ().
Length of major axis = 2a =8
Length of minor axis = 2b =6
Eccentricity, e
Length of latus rectum =
In each of the, find the coordinates of the foci, the vertices, the length of major axis, the minor axis, the eccentricity and the length of the latus rectum of the ellipse.
The given equation is =1 or =1.
Here, the denominator of is greater than the denominator of.
Therefore, the major axis is along the x-axis, while the minor axis is along the y-axis.
On comparing the given equation with =1, we obtain b =5 and a =10.
c = = = 5
Therefore,
The coordinates of the foci are ().
The coordinate of the vertices are (0,).
Length of major axis = 2a = 20
Length of minor axis = 2b = 10
Eccentricity, e
Length of latus rectum =
In each of the, find the coordinates of the foci, the vertices, the length of major axis, the minor axis, the eccentricity and the length of the latus rectum of the ellipse.
The given equation is =1 or =1.
Here, the denominator of is greater than the denominator of
Therefore, the major axis is along the x-axis, while the minor axis is along the y-axis.
On comparing the given equation with =1, we obtain a =7 and b =6.
c = =
Therefore,
The coordinates of the foci are ().
The coordinate of the vertices are ( ).
Length of major axis = 2a = 14
Length of minor axis = 2b = 12
Eccentricity, e =
Length of latus rectum =
In each of the, find the coordinates of the foci, the vertices, the length of major axis, the minor axis, the eccentricity and the length of the latus rectum of the ellipse.
The given equation is =1 or =1.
Here, the denominator of is greater than the denominator of.
Therefore, the major axis is along the x-axis, while the minor axis is along the y-axis.
On comparing the given equation with =1, we obtain b =10 and a =20.
c = = = 10
Therefore,
The coordinates of the foci are ().
The coordinate of the vertices are (0,).
Length of major axis = 2a = 40
Length of minor axis = 2b = 20
Eccentricity, e
Length of latus rectum =
In each of the, find the coordinates of the foci, the vertices, the length of major axis, the minor axis, the eccentricity and the length of the latus rectum of the ellipse.
36x2 + 4y2 = 144
The given equation is 36x2 + 4y2 = 144.
It can be written as
36x2 + 4y2 = 144
Or, =1
Or, =1. …………(1)
Here, the denominator of is greater than the denominator of.
Therefore, the major axis is along the x-axis, while the minor axis is along the y-axis.
On comparing the given equation with =1, we obtain b =2 and a =6.
c = = = 4
Therefore,
The coordinates of the foci are ().
The coordinate of the vertices are (0, ).
Length of major axis = 2a = 12
Length of minor axis = 2b = 4
Eccentricity, e
Length of latus rectum =
In each of the, find the coordinates of the foci, the vertices, the length of major axis, the minor axis, the eccentricity and the length of the latus rectum of the ellipse.
16x2 + y2 = 16
The given equation is 16x2 + y2 = 16.
It can be written as
16x2 + y2 = 16
Or, =1
Or, =1. ………… (1)
Here, the denominator of is greater than the denominator of.
Therefore, the major axis is along the x-axis, while the minor axis is along the y-axis.
On comparing the given equation with =1, we obtain b =1 and a =4.
c = =
Therefore,
The coordinates of the foci are ().
The coordinate of the vertices are (0, ).
Length of major axis = 2a = 8
Length of minor axis = 2b = 2
Eccentricity, e
Length of latus rectum =
In each of the, find the coordinates of the foci, the vertices, the length of major axis, the minor axis, the eccentricity and the length of the latus rectum of the ellipse.
4x2 + 9y2 = 36
The given equation is 4x2 + 9y2 = 36.
It can be written as
4x2 + 9y2 = 36
Or, =1
Or, =1. ………… (1)
Here, the denominator of is greater than the denominator of.
Therefore, the major axis is along the x-axis, while the minor axis is along the y-axis.
On comparing the given equation with =1, we obtain a =3 and b =2.
c = =
Therefore,
The coordinates of the foci are ().
The coordinate of the vertices are ( ).
Length of major axis = 2a = 6
Length of minor axis = 2b = 4
Eccentricity, e
Length of latus rectum =
In each of the following, find the equation for the ellipse that satisfies the given conditions:
Vertices ( 5, 0), foci ( 4, 0)
Vertices (), foci ( ).
Here, the vertices are on the x-axis.a
Therefore, the equation of the ellipse will be of the form =1, where a is the semi-major axis.
Accordingly, a=5 and c = 4.
It is known that a2 = b2+c2.
52 = b2+42
25 = b2 + 16
b2 = 25 – 16
b = = 3
Thus, the equation of the ellipse is =1 or = 1.
In each of the following, find the equation for the ellipse that satisfies the given conditions:
Vertices (0, 13), foci (0, 5)
Vertices (), foci (0,).
Here, the vertices are on the x-axis.
Therefore, the equation of the ellipse will be of the form =1, where a is the semi-major axis.
Accordingly, a=13 and c = 5.
It is known that a2 = b2+c2.
132 = b2+52
169 = b2 + 15
b2 = 169 – 125
b = = 12
Thus, the equation of the ellipse is =1 or = 1.
In each of the following, find the equation for the ellipse that satisfies the given conditions:
Vertices ( 6, 0), foci ( 4, 0)
Vertices (6, 0), foci (4, 0).
Here, the vertices are on the x-axis.
Therefore, the equation of the ellipse will be of the form =1, where a is the semi-major axis.
Accordingly, a=6 and c = 4.
It is known that a2 = b2+c2.
62 = b2+42
36 = b2 + 16
b2 = 36 – 16
b =
Thus, the equation of the ellipse is =1 or = 1.
In each of the following, find the equation for the ellipse that satisfies the given conditions:
Ends of major axis ( 3, 0), ends of minor axis (0, 2)
Ends of major axis (), ends of minor axis ().
Here, the major axis is along the x-axis.
Therefore, the equation of the ellipse will be of the form =1, where a is the semi-major axis.
Accordingly, a=3 and b = 2.
Thus, the equation for the ellipse = 1 i.e., = 1.
In each of the following, find the equation for the ellipse that satisfies the given conditions:
Ends of major axis (0, ), ends of minor axis ( 1, 0)
Ends of major axis (0,), ends of minor axis ().
Here, the major axis is along the x-axis.
Therefore, the equation of the ellipse will be of the form =1, where a is the semi-major axis.
Accordingly, a= and b = 1.
Thus, the equation for the ellipse = 1 or, = 1.
In each of the following, find the equation for the ellipse that satisfies the given conditions:
Length of major axis 26, foci ( 5, 0)
Length of major axis = 26; foci = ().
Since the foci are on the x-axis, the major axis is along the x-axis.
Therefore, the equation of the ellipse will be of the form =1, where a is the semi-major axis.
Accordingly, 2a =26 a = 13 and c=5.
It is known that a2 = b2+c2.
132 = b2+42
169 = b2 + 25
b2 = 169 – 25
b = = 12
Thus, the equation of the ellipse is =1 or = 1.
In each of the following, find the equation for the ellipse that satisfies the given conditions:
Length of minor axis 16, foci (0, 6).
Length of major axis = 26; foci = ().
Since the foci are on the x-axis, the major axis is along the x-axis.
Therefore, the equation of the ellipse will be of the form =1, where a is the semi-major axis.
Accordingly, 2b =16 b = 8 and c=6.
It is known that a2 = b2+c2.
a2 = 82+62 = 64+36 =100
b = = 10
Thus, the equation of the ellipse is =1 or = 1.
In each of the following, find the equation for the ellipse that satisfies the given conditions:
Foci ( 3, 0), a = 4
Foci = (), a=4
Since the foci are on the x-axis, the major axis is along the x-axis.
Therefore, the equation of the ellipse will be of the form =1, where a is the semi-major axis.
Accordingly, c = 3 and a=4.
It is known that a2 = b2+c2.
a2 = 82+62 = 64+36 =100
16 = b2 + 9
b2 = 16 – 9 = 7
Thus, the equation of the ellipse is = 1.
In each of the following, find the equation for the ellipse that satisfies the given conditions:
b = 3, c = 4, centre at the origin; foci on the x axis.
It is given that b = 3, c=4, centre at the origin; foci on the x axis.
Since the foci are on the x-axis, the major axis is along the x-axis.
Therefore, the equation of the ellipse will be of the form =1, where a is the semi-major axis.
Accordingly, b = 3 and c=4.
It is known that a2 = b2+c2.
a2 = 32+42 = 9+16 =25
a =5
Thus, the equation of the ellipse is or = 1.
In each of the following, find the equation for the ellipse that satisfies the given conditions:
Centre at (0,0), major axis on the y-axis and passes through the points (3, 2) and (1,6).
Since the center is at (0,0) and the major axis is on the y- axis, the equation of the ellipse will be of the form
=1 ………………….(1)
Where, a is the semi - major axis
The ellipse passes through points (3, 2) and (1, 6). Hence,
=1 …………………… (2)
=1……………………… (3)
On solving equation (2) and (3), we obtain b2 = 10 and a2 = 40.
Thus, the equation of the ellipse is = 1 or 4x2 + y 2 = 40.
In each of the following, find the equation for the ellipse that satisfies the given conditions:
Major axis on the x-axis and passes through the points (4,3) and (6,2).
Since the major axis is on the x-axis, the equation of the ellipse will be the form
=1 …………………. (1)
Where, a is the semi - major axis
The ellipse passes through points (4, 3) and (6,2). Hence,
Putting x = 4 and y = 3, we get,=1 …………………… (2)
Putting, x = 6 and y = 2, we get,……………………… (3)
Let a2 = m and b2 = nOn solving equation (2) and (3), we obtain a2 = 52 and b2 = 13.
Thus, the equation of the ellipse is = 1 or x2 + 4y2 = 52.
In each of the, find the coordinates of the foci and the vertices, the eccentricity and the length of the latus rectum of the hyperbolas.
The given equation is or
On comparing this equation with the standard equation of hyperbola
, we get,
a = 4 and b = 3,
We know, a2 + b2 = c2
Thus,
c2 = 42 + 32 =25
⇒ c = 5
Therefore,
The coordinates of the foci are (5,0).
The coordinates of the vertices are (4, 0).
Eccentricity, e =
Length of latus rectum =
In each of the, find the coordinates of the foci and the vertices, the eccentricity and the length of the latus rectum of the hyperbolas.
The given equation is or
On comparing this equation with the standard equation of hyperbola
, we get,
a = 4 and b =,
We know, a2 + b2 = c2
Thus,
c2 = 32 + = 36
⇒ c = 6
Therefore,
The coordinates of the foci are (0, 6).
The coordinates of the vertices are (0, 3).
Eccentricity, e =
Length of latus rectum =
In each of the, find the coordinates of the foci and the vertices, the eccentricity and the length of the latus rectum of the hyperbolas.
9y2 – 4x2 = 36
The given equation is 9y2 – 4x2 = 36
We can re-write the given as
or ………..(1)
On comparing this equation (1) with the standard equation of hyperbola
, we get,
a = 2 and b =3
We know, a2 + b2 = c2
Thus,
c2 = 4 + 9 = 13
⇒ c =
Therefore,
The coordinates of the foci are (0, ).
The coordinates of the vertices are (0, 2).
Eccentricity, e =
Length of latus rectum =
In each of the, find the coordinates of the foci and the vertices, the eccentricity and the length of the latus rectum of the hyperbolas.
16x2 – 9y2 = 576
The given equation is 16y2 – 9x2 = 576
We can re-write the given as
Or ……….. (1)
On comparing this equation (1) with the standard equation of hyperbola
, we get,
a = 6 and b =8
We know, a2 + b2 = c2
Thus,
c2 = 36 + 64 = 100
⇒ c = 10
Therefore,
The coordinates of the foci are (10, 0).
The coordinates of the vertices are (6, 0).
Eccentricity, e =
Length of latus rectum =
In each of the, find the coordinates of the foci and the vertices, the eccentricity and the length of the latus rectum of the hyperbolas.
5y2 – 9x2 = 36
The given equation is 5y2 – 9x2 = 36
We can re-write the given as
Or ……….. (1)
On comparing this equation (1) with the standard equation of hyperbola
, we get,
a = and b =2
We know, a2 + b2 = c2
Thus,
c2 = =
⇒ c =
Therefore,
The coordinates of the foci are
The coordinates of the vertices are .
Eccentricity, e =
Length of latus rectum =
In each of the, find the coordinates of the foci and the vertices, the eccentricity and the length of the latus rectum of the hyperbolas.
49y2 – 16x2 = 784.
The given equation is 49y2 – 16x2 = 784
We can re-write the given as
Or ……….. (1)
On comparing this equation (1) with the standard equation of hyperbola
, we get,
a = 4 and b =7
We know, a2 + b2 = c2
Thus,
c2 = 16 + 49 = 65
⇒ c =
Therefore,
The coordinates of the foci are (0, ).
The coordinates of the vertices are (0, 4).
Eccentricity, e =
Length of latus rectum =
In each of the, find the equations of the hyperbola satisfying the given conditions.
Vertices ( 2, 0), foci ( 3, 0)
Vertices ( 2, 0), foci ( 3, 0)
Here, the vertices are on the x-axis.
Thus,
The equation of the hyperbola is of the form
Since, the vertices are (2,0), a = 2
Since, the foci are (3, 0), c= 3
We know that, a2 + b2 = c2
Thus, 22 + b2 = 32
⇒ b2 = 9 – 4 = 5
Hence, the equation of the hyperbola is
In each of the, find the equations of the hyperbola satisfying the given conditions.
Vertices (0, 5), foci (0, 8)
Vertices (0, 5), foci (0, 8)
Here, the vertices are on the y-axis.
Thus,
The equation of the hyperbola is of the form
Since, the vertices are (0, 5), a = 5
Since, the foci are (0, 8), c= 8
We know that, a2 + b2 = c2
Thus, 52 + b2 = 82
⇒ b2 = 64 – 25 = 39
Hence, the equation of the hyperbola is
In each of the, find the equations of the hyperbola satisfying the given conditions.
Vertices (0, 3), foci (0, 5)
Vertices (0, 3), foci (0, 5)
Here, the vertices are on the y-axis.
Thus,
The equation of the hyperbola is of the form
Since, the vertices are (0, 3), a = 3
Since, the foci are (0, 5), c= 5
We know that, a2 + b2 = c2
Thus, 32 + b2 = 52
⇒ b2 = 25 – 9 = 16
Hence, the equation of the hyperbola is
In each of the, find the equations of the hyperbola satisfying the given conditions.
Foci ( 5, 0), the transverse axis is of length 8.
Foci ( 5, 0), the transverse axis is of length 8.
Here, the foci are on x-axis.
Thus,
The equation of the hyperbola is of the form
Since, the foci are (5, 0), c= 5
Since, the length of the transverse axis is 8,
2a = 8 ⇒ a = 4
We know that, a2 + b2 = c2
42 + b2 = 52
⇒ b2 = 25 – 16 = 9
Hence, the equation of the hyperbola is
In each of the, find the equations of the hyperbola satisfying the given conditions.
Foci (0, 13), the conjugate axis is of length 24.
Foci (0, 13), the conjugate axis is of length 24.
Here, the foci are on y-axis.
Thus,
The equation of the hyperbola is of the form
Since, the foci are (0, 13), c= 13
Since, the length of the conjugate axis is 24,
2b = 24 ⇒ b = 12
We know that, a2 + b2 = c2
a2 + 122 = 132
⇒ a2 = 169 – 144 = 25
Hence, the equation of the hyperbola is
In each of the, find the equations of the hyperbola satisfying the given conditions.
Foci ( 3, 0), the latus rectum is of length 8.
Foci ( 3, 0), the latus rectum is of length 8.
Here, the foci are on x-axis.
Thus,
The equation of the hyperbola is of the form
Since, the foci are (), c=
Length of latus rectum = 8
⇒
⇒ b2 = 4a
We know that, a2 + b2 = c2
a2 + 4a = 45
⇒ a2 + 4a -45 = 0
⇒ a2 + 9a – 5a -45 = 0
⇒ (a +9)(a -5) = 0
⇒ A = -9,5
Since, a is non – negative, a = 5
Thus, b2 = 4a = 4 × 5 = 20
Hence, the equation of the hyperbola is
In each of the, find the equations of the hyperbola satisfying the given conditions.
Foci ( 4, 0), the latus rectum is of length 12
Foci ( 4, 0), the latus rectum is of length 12
Here, the foci are on x-axis.
Thus,
The equation of the hyperbola is of the form
Since, the foci are ( 4, 0), c = 4
Length of latus rectum = 12
⇒
⇒ b2 = 6a
We know that, a2 + b2 = c2
a2 + 6a = 16
⇒ a2 + 6a -16 = 0
⇒ a2 + 8a – 2a - 16 = 0
⇒ (a +8)(a -2) = 0
⇒ A = -8, 2
Since, a is non – negative, a = 2
Thus, b2 = 6a = 6 × 2 = 12
Hence, the equation of the hyperbola is
In each of the, find the equations of the hyperbola satisfying the given conditions.
vertices ( 7,0), e =
vertices ( 7,0), e =
Here, the vertices are on the x- axis
Thus, the equation of the hyperbola is of the form
Since, the vertices are ( 7,0), a = 7
It is given that e =
We know that, a2 + b2 = c2
Thus,
72 + b2 =
Thus, the equation of the hyperbola is
In each of the, find the equations of the hyperbola satisfying the given conditions.
Foci (0, ), passing through (2, 3)
Foci (0, ), passing through (2, 3)
Here, the foci are on y-axis.
Thus,
The equation of the hyperbola is of the form
Since, the foci are (, 0), c =
We know that, a2 + b2 = c2
⇒ b2 = 10 – a2 …………..(1)
Since, the hyperbola passes through point (2, 3)
……………(2)
From equations (1) and (2), we get,
⇒ 9(10 – a2) – 4a2 = a2(10 –a2)
⇒ 90 – 9a2 – 4a2 = 10a2 – a4
⇒ a4 -23a2 + 90 = 0
⇒ a4 -18a2 -5a2+ 90 = 0
⇒ a2(a2 -18) -5(a2 -18) = 0
⇒ (a2 – 18)(a2 -5) = 0
⇒ a2 = 18 or 5
In hyperbola, c>a that is c2> a2
Thus, a2 = 5
⇒ b2 = 10 – a2 = 10 – 5 = 5
Hence, the equation of the hyperbola is
If a parabolic reflector is 20 cm in diameter and 5 cm deep, find the focus.
The origin of the coordinate plane is taken at the vertex of the parabolic reflector in such a way that the axis of the reflector is along the positive x – axis.
This can be diagrammatically represented as
The equation of the parabola is of the form y2 = 4ax (as it is opening to the right)
Since, the parabola passes through point A(10, 5), 102 = 4a(5)
⇒ 100 = 20a
⇒ a = = 5
Therefore, the focus of the parabola is (a, 0) = (5,0), which is the mid – point of the diameter.
Hence, the focus of the reflector is at the mid-point of the diameter.
An arch is in the form of a parabola with its axis vertical. The arch is 10 m high and 5 m wide at the base. How wide is it 2 m from the vertex of the parabola?
The origin of the coordinate plane is taken at the vertex of the arch in such a way that its vertical axis is along the negative y –axis.
This can be diagrammatically represented as
The equation of the parabola is of the form x2 = -4ay (as it is opening downwards).
It is given that at base arch is 10m high and 5m wide.It can be clearly seen that the parabola passes through point
Therefore, the arch is in the form of a parabola whose equation is
When, y = -2,
Hence, when the arch is 2m from the vertex of the parabola, its width is approximately 2.23m.
The cable of a uniformly loaded suspension bridge hangs in the form of a parabola.
The roadway which is horizontal and 100 m long is supported by vertical wires attached to the cable, the longest wire being 30 m and the shortest being 6 m.
Find the length of a supporting wire attached to the roadway 18 m from the middle.
The vertex is at the lowest point of the cable. The origin of the coordinate plane is taken as the vertex of the parabola, while its vertical axis is taken along the positive y –axis. This can be diagrammatically represented as
Here, AB and OC are the longest and the shortest wires, respectively, attached to the cable.
DF is the supporting wire attached to the roadways, 18m from the middle.
Here, AB = 30m, OC = 6m, and BC = 50m.
The equation of the parabola is of the from x2 = 4ay (as it is opening upwards).
The coordinates of point A are (50, 30 -6) = (50, 24)
Since, A(50, 24) is a point on the parabola.
(50)2 = 4a(24)
⇒ a =
Thus, Equation of the parabola,
The x – coordinate of point D is 18.
Hence, at x = 18,
6(18)2 = 625y
⇒ y =
⇒ y = 3.11(approx.)
Thus, DE = 3.11 m
DF = DE +EF = 3.11m +6m = 9.11m
Thus, the length of the supporting wire attached to the roadway 18m from the middle is approximately 9.11m.
An arch is in the form of a semi-ellipse. It is 8 m wide and 2 m high at the centre. Find the height of the arch at a point 1.5 m from one end.
Since, the height and width of the arc from the centre is 2m and 8m respectively, it is clear that the length of the major axis is 8m, while the length of the semi- minor axis is 2m.
The origin of the coordinate plane is taken as the centre of the ellipse, while the major axis is taken along the x-axis. Hence, the semi- ellipse can be diagrammatically represented as
The equation of the semi – ellipse will be of the from ……..(1)
Let A be a point on the major axis such that AB = 1.5m.
Draw ACOB.
OA = (4 – 1.5)m = 2.5m
The x – coordinate of point C is 2.5
On substituting the value of x with 2.5 in equation (1), we get,
⇒ y2 = 2.4375
⇒ y = 1.56(approx.)
Thus, AC = 1.56m
Hence, the height of the arch at a point 1.5m from one end is approximately 1.56m.
A rod of length 12 cm moves with its ends always touching the coordinate axes. Determine the equation of the locus of a point P on the rod, which is 3 cm from the end in contact with the x-axis.
Let AB be the rod making an angle Ɵ with OX and P(x,y) be the point on it such that AP = 3cm.
Then, PB = AB – AP = (12 – 3)cm = 9cm [AB = 12cm]
From P, draw PQ OY and PROX.
In ΔPBQ,
Since, sin2Ɵ +cos2Ɵ = 1,
Or,
Thus, the equation of the locus of point P on the rod is .
Find the area of the triangle formed by the lines joining the vertex of the parabola x2 = 12y to the ends of its latus rectum.
The given parabola is x2 = 12y.
On comparing this equation with x2 = 4ay, we get,
4a = 12
⇒ a = 3
Thus, the coordinates of foci are S(0,a) = S(0,3).
Let AB be the latus rectum of the given parabola.
The given parabola can be roughly drawn as
At y = 3, x2 = 12(3)
⇒ x2 = 36
⇒ x = 6
Thus, the coordinates of A are (-6,3), while the coordinates of B are (6,3)
Therefore, the vertices of ΔOAB are O(0,0), A (-6,3) and B(6,3).
Area of ΔOAB = unit2
= unit2
= unit2
= unit2
unit2
=18unit2
A man running a racecourse notes that the sum of the distances from the two flag posts from him is always 10 m and the distance between the flag posts is 8 m.
Find the equation of the posts traced by the man.
Let A and B be the positions of the two flag posts and P(x,y) be the position of the man.
Accordingly, PA + PB = 10.
We know that if a point moves in plane in such a way that the sum of its distance from two fixed point is constant, then the path is an ellipse and this constant value is equal to the length of the major axis of the ellipse.
Therefore, the path described b the man is an ellipse where the length of the major axis is 10m, while points A and B are the foci.
Taking the origin of the coordinate plane as the centre of the ellipse, while taking the major axis along the x- axis, the ellipse can be diagrammatically represented as
The equation of the ellipse will be of the form , where a is the semi-major axis.
Accordingly, 2a = 10 ⇒ a = 5
Distance between the foci (2c) = 8
⇒ c = 4
On using the relation, c = , we get,
4 =
⇒ 16 = 25 – b2
⇒ b2 = 25 -1 6 = 9
⇒ b = 3
Hence, equation of the path traced by the man is
An equilateral triangle is inscribed in the parabola y2 = 4 ax, where one vertex is at the vertex of the parabola. Find the length of the side of the triangle.
Let OAB be the equilateral triangle inscribed in parabola y2 = 4ax.
Let AB intersect the x – axis at point C.
Let OC = k
From the equation of the given parabola, we have,
y2 = 4ak
⇒ y = 2
Thus, the respective coordinates of points A and B are (k, 2 ), and (k, -2)
AB = CA + CB = 2
Since, OAB is an equilateral triangle, OA2 = AB2.
Thus,
⇒ k2 + 4ak = 16ak
⇒ k2 = 12ak
⇒ k = 12a
Thus, AB =
Thus, the side of the equilateral triangle inscribed in parabola y2 = 4ax is .