All Exams  >   JEE  >   Chapter-wise Tests for JEE Main & Advanced  >   All Questions

All questions of Circle for JEE Exam

 The equation of circle whose centre is (2, 1) and which passes through the point (3, – 5) is:
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'B'. Can you explain this answer?

Poonam Reddy answered
 Radius of circle is given by -
r = √[(h-x1)² + (k-y1)²]
r = √[(2-3)² + (1+5)²]
r = √(-1² + 6²)
r = √(1 + 36)
r = √37
if centre (2,-]1) and radius=√26 are given,
(x-h)2+(y-k)2=r2
equation is (x-2)2 + (y-1)2 = (√37)2
x2 + 4 - 4x + y2 + 1 - 2y = 37
x2 + y2 - 4x - 2y - 32 = 0

The equation of the circle passing through (0, 0) and making intercepts 2 and 4 on the coordinate axes is:
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'C'. Can you explain this answer?

Geetika Shah answered
The circle intercept the co-ordinate axes at a and b. it means x - intercept at ( a, 0) and y-intercept at (0, b) .
Now, we observed that circle passes through points (0, 0) , (a, 0) and (0, b) .
we also know, General equation of circle is
x² + y² + 2gx + 2fy + C = 0
when point (0,0)
(0)² + (0)² + 2g(0) + 2f(0) + C = 0
0 + 0 + 0 + 0 + C = 0
C = 0 -------(1)
when point (a,0)
(a)² + (0)² + 2g(a) + 2f(0) + C = 0
a² + 2ag + C = 0
from equation (1)
a² + 2ag = 0
a(a + 2g) = 0
g = -a/2
when point ( 0, b)
(0)² + (b)² + 2g(0) + 2f(b) + C = 0
b² + 2fb + C = 0
f = -b/2
Now, equation of circle is
x² + y² + 2x(-a/2) + 2y(-b/2) + 0 = 0 { after putting values of g, f and C }
x² + y² - ax - by = 0
As we know that, a=2, b=4
x^2 + y^2 - 2x - 4y = 0

 The centre and radius of the circle x2 + y2 + 4x – 6y = 5 is:
  • a)
    (2, – 3), 2√2
  • b)
    (– 2, 3), 3√2
  • c)
    (– 2, 3), 2√2
  • d)
    (2, – 3), 3√2
Correct answer is option 'B'. Can you explain this answer?

Riya Banerjee answered
x2+y2+4x-6y=5
Circle Equation
(x-a)2+(y-b)2=r2 is the circle equation with a radius r, centered at (a,b)
Rewrite x2+y24x-6y=5 in the form of circle standard circle equation
(x-(-2))
2
+(y-3)2=(3
√2)2
Therefore the circle properties are:

(a,b) = (-2,3), r = 3√2

The point diametrically opposite to the point P(1, 0) on the circle x2 + y2 + 2x + 4y – 3 = 0 is [2008]
  • a)
    (3, – 4)
  • b)
    (–3, 4)
  • c)
    (–3, –4)
  • d)
    (3, 4)
Correct answer is option 'C'. Can you explain this answer?

Srestha Iyer answered
The given circle is  x2 + y2 + 2x + 4y –3 = 0
Centre (–1, –2)
Let Q (α, β) be the point diametrically opposite to the point P(1, 0),
⇒ α = –3, β = – 4, So, Q is (–3, –4)

A parabola has the origin as its focus and the line x = 2 as the directrix. Then the vertex of the parabola is at [2008]
  • a)
    (0, 2)
  • b)
    (1, 0)
  • c)
    (0, 1)
  • d)
    (2, 0)
Correct answer is option 'B'. Can you explain this answer?

Geetika Shah answered
Vertex of a parabola is the mid point of focus and the point
where directrix meets the axis of the parabola.
Here focus is O(0, 0) and directxix meets the axis at B(2, 0)
∴ Vertex of the parabola is (1, 0)

The equation of the circle having the lines y2 – 2y + 4x – 2xy = 0 as its normals & passing through the point (2, 1) is
  • a)
    x2 + y2 – 2x – 4y + 3 = 0
  • b)
    x2 + y2 – 2x + 4y – 5 = 0
  • c)
    x2 + y2 + 2x + 4y – 13 = 0
  • d)
    None
Correct answer is option 'A'. Can you explain this answer?

Geetika Shah answered
The normal line to circle is →y² - 2 y + 4 x -2 xy=0
→ y(y-2) - 2x(y-2)=0
→ (y-2)(y-2x)=0
the two lines are , y=2 and 2 x -y =0
The point of intersection of normals are centre of circle.
→ Put , y=2 in 2 x -y=0, we get
→2 x -2=0
→2 x=2
→ x=1
So, the point of intersection of normals is (1,2) which is the center of circle.
Also, the circle passes through (2,1).
Radius of circle is given by distance formula = [(1-2)² + (2-1)²]½ 
=(1+1)½ =(2)½
The equation of circle having center (1,2) and radius √2 is
= (x-1)²+(y-2)²=[√2]²
→ (x-1)²+(y-2)²= 2
x²+y² -2x-4y+3 = 0

The equations of the tangents drawn from the point (0, 1) to the circle x2 + y2 - 2x + 4y = 0 are
  • a)
    2x - y + 1 = 0, x + 2y - 2 = 0
  • b)
    2x - y - 1 = 0, x + 2y - 2 = 0
  • c)
    2x - y + 1 = 0, x + 2y + 2 = 0
  • d)
    2x - y - 1 = 0, x + 2y + 2 = 0
Correct answer is option 'A'. Can you explain this answer?

Geetika Shah answered
Let equation of tangent with slope =m and point (0,1)
(y−1)=m(x−0)⇒y=mx+1
Intersection point
x2+(mx+1)2−2x+4(mx+1)=0
(1+m2)x2+(−2+6m)x+5=0
For y=mx+1 to be tangent, discriminant =0
(6m−2)2−4×5(1+m2)=0
36m2+4−24m−20m2+20=0
16m2−20m+24=0
⇒ 2m2−3m−2=0
(2m+1)(m−2)=0

The locus of the mid-points of the chords of the circle x2 + y2 – 2x – 4y – 11 = 0 which subtend 60º at the centre is
  • a)
    x2 + y2 – 4x – 2y – 7 = 0
  • b)
    x2 + y2 + 4x + 2y – 7 = 0
  • c)
    x2 + y2 – 2x – 4y – 7 = 0
  • d)
    x2 + y2 + 2x + 4y + 7 = 0
Correct answer is option 'C'. Can you explain this answer?

Preeti Iyer answered
Let AB be the chord of the circle and P be the midpoint of AB.
It is known that perpendicular from the center bisects a chord.
Thus △ACP is a right-angled triangle.
Now AC=BC= radius.
The equation of the give circle can be written as
(x−1)2+(y−2)2=16
Hence, centre C=(1,2) and radius =r=4 units.
PC=ACsin60degree
= rsin60degree
= 4([2(3)½]/2
= 2(3)1/2 units
Therefore, PC=2(3)1/2
⇒ PC2=12
⇒ (x−1)2+(y−2)2=12
⇒ x2+y2−2x−4y+5=12
⇒ x2+y2−2x−4y−7=0

y = √3x + c1 & y = √3x + c2 are two parallel tangents of a circle of radius 2 units, then |c1 – c2| is equal to
  • a)
    8
  • b)
    4
  • c)
    2
  • d)
    1
Correct answer is option 'A'. Can you explain this answer?

Anmol Chauhan answered
For both lines to be parallel tangent the distance between both lines
should be equal to the diameter of the circle
⇒ 4 = |c1−c2|/(1+3)1/2
⇒∣c1−c2∣ = 8

Number of different circles that can be drawn touching 3 lines, no two of which are parallel and they are neither coincident nor concurrent, are
  • a)
    1
  • b)
    2
  • c)
    3
  • d)
    4
Correct answer is option 'D'. Can you explain this answer?

Raghav Bansal answered
 If three lines are given such that no two of them are parallel and they are not concurrent then a definite triangle is formed by them. There are four circles which touch sides of a triangle (3-excircles and 1-incircle).

The ellipse  x2 + 4y= 4 is inscribed in a rectangle aligned with the coordinate axes, which in turn is inscribed in another ellipse that passes through the point (4, 0). Then the equation of the ellipse is : [2009]
  • a)
    x2 + 12y2= 16
  • b)
    4 x2 + 48y2= 48
  • c)
    4 x2 + 64y= 48
  • d)
    x2 + 16y2= 16
Correct answer is option 'A'. Can you explain this answer?

Anushka Ahuja answered
Solution:

Given that the ellipse x^2/4 + y^2 = 1 is inscribed in a rectangle aligned with the coordinate axes and this rectangle is inscribed in another ellipse that passes through the point (4, 0).

Let's find the equation of the outer ellipse.

Step 1: Find the coordinates of the four corners of the rectangle.
The corners of the rectangle can be obtained by solving the equation of the ellipse with x = ±2 and y = ±1.
For x = 2, we have 4/4 + y^2 = 1, which gives y = ±√3.
So, the coordinates are (2, √3) and (2, -√3).
Similarly, for x = -2, we have 4/4 + y^2 = 1, which gives y = ±√3.
So, the coordinates are (-2, √3) and (-2, -√3).

Step 2: Find the equation of the ellipse passing through the points (2, √3), (2, -√3), (-2, √3), and (-2, -√3).
Using the standard form of an ellipse, the equation is:
(x - h)^2/a^2 + (y - k)^2/b^2 = 1, where (h, k) is the center of the ellipse, and a and b are the semi-major and semi-minor axes, respectively.

Step 3: Find the center of the ellipse.
The center of the ellipse is the midpoint of the diagonals of the rectangle.
The midpoint of the diagonals is ((2 + (-2))/2, (√3 + (-√3))/2) = (0, 0).

Step 4: Find the semi-major and semi-minor axes.
The semi-major axis is the distance from the center to one of the corners of the rectangle, which is 2.
The semi-minor axis is the distance from the center to one of the sides of the rectangle, which is 1.

Therefore, the equation of the outer ellipse is:
(x - 0)^2/2^2 + (y - 0)^2/1^2 = 1
Simplifying, we get x^2/4 + y^2 = 1.

Hence, the correct answer is option A) x^2 - 12y^2 = 16.

 Pair of tangents are drawn from every point on the line 3x + 4y = 12 on the circle x2+ y2 = 4. Their variable chord of contact always passes through a fixed point whose co-ordinates are
  • a)
  • b)
  • c)
    (1, 1)
  • d)
     
Correct answer is option 'D'. Can you explain this answer?

Geetika Shah answered
Let P(x1,y1) be a point on the line 3x + 4y = 12
Equation of variable chord of contact of P(x1,y1) w.r.t circle x2 + y2 = 4 
xx1 + yy1 − 4 = 0   ...(1)
Also 3x1 + 4y1 − 12 = 0
⇒ x1 + 4/3y1 − 4 = 0   ...(2)
Comparing (1) and (2), we get
x = 1; y = 4/3
∴ Variable chord of contact always passes through (1, 4/3)

The equation of the chord of x2 + y2 - 4x + 6y + 3 = 0 whose mid point is (1, -2) is
  • a)
    x + y + 1 = 0
  • b)
    2x + 3y + 4 = 0
  • c)
    x - y - 3 = 0
  • d)
    Not existing
Correct answer is option 'C'. Can you explain this answer?

Shounak Datta answered
Solution:

Given equation is x^2 + y^2 - 4x - 6y + 3 = 0

We need to find the equation of the chord whose midpoint is (1,-2).

Midpoint of the chord = (1,-2)

Let the co-ordinates of the end points of the chord be (x1, y1) and (x2, y2)

Therefore, the midpoint of the chord is ((x1+x2)/2, (y1+y2)/2)

Given that midpoint of the chord is (1,-2)

=> (x1+x2)/2 = 1 and (y1+y2)/2 = -2

=> x1+x2 = 2 and y1+y2 = -4

Let the equation of the chord be y = mx + c

By substituting y = mx + c in the given equation, we get

x^2 + (mx + c)^2 - 4x - 6(mx + c) + 3 = 0

=> (m^2 + 1)x^2 + (2mc - 4m - 6)x + c^2 - 6c + 3 = 0

Since the given line is a chord of the circle, it should intersect the circle at two points.

Therefore, the discriminant of the above quadratic equation should be greater than or equal to 0.

=> (2mc - 4m - 6)^2 - 4(m^2 + 1)(c^2 - 6c + 3) >= 0

Simplifying the above inequality, we get

=> (m^2 + 1)c^2 - 2m(3 + 2x) c + (x^2 - 4x + 3m^2 - 6m + 3) >= 0

Since the given line passes through (1,-2), we can substitute x=1 and y=-2 in the equation of the line.

=> -2 = m + c

=> c = -2 - m

Substituting this value of c in the above inequality, we get

=> (m^2 + 1)(m^2 - 4m + 6) >= 0

The above inequality is satisfied for all values of m.

Therefore, the equation of the chord is of the form x - y - 3 = 0.

Hence, option (C) is the correct answer.

Number of points (x, y) having integral coordinates satisfying the condition x2 + y2 < 25 is
  • a)
    69
  • b)
    80
  • c)
    81
  • d)
    77
Correct answer is option 'A'. Can you explain this answer?

Hansa Sharma answered
Since x2+y2<25 and a and y are integers, the possible values of x and y∈(0,±1,±2,±3,±4,). 
Thus,x and y can be chosen in 9 ways each and (x,y) can be chosen in 9×9=81 ways.
However, we have to exclude cases (±3,±4),(±4,±3)
and (±4,±4)i.e.,3×4=12
Hence, the number of permissible values = 81−12=69

If P(2, 8) is an interior point of a circle x2 + y2 –2x + 4y – p = 0 which neither touches nor intersects the axes, then set for p is
  • a)
    p < -1
  • b)
    p < -4
  • c)
    p > 96
  • d)
    φ
Correct answer is option 'D'. Can you explain this answer?

Lavanya Menon answered
For internal point p(2, 8),  4 + 64 – 4 + 32 – p < 0 ⇒ p > 96 
and x intercept = therefore 1 + p < 0
⇒ p < -1 and  y intercept = ⇒ p < -4
Hence (D) is the correct answer.

If a be the radius of a circle which touches x-axis at the origin, then its equation is
  • a)
    x2 + y2 + ax = 0
  • b)
    x2 + y2 ± 2ya = 0
  • c)
    x2 + y2 ± 2xa = 0
  • d)
    x2 + y2 + ya = 0
Correct answer is option 'B'. Can you explain this answer?

Sushant Ghosh answered
The equation of the circle  with centre at (h,k) and radius equal to a is (x−h)+(y−k)= a2
 When the circle passes through the origin  and centre lies on x− axis 
⇒h = a and k = 0
Then the equation (x−h)2+(y−k)2=abecomes (x−a)2+y2=a2
If a circle passes through the origin and centre lies on x−axis then the abscissa will be equal to the radius of the circle and the y−co-ordinate of the centre will be zero Hence, the equation of the circle will be of the form 
(x±a)2+y2=a2⇒x2+a±2ax+y2=a2
=x2 +y±2ax=0 is the required equation of the circle.

The locus of the centre of a circle which touches externally the circle, x2 + y2 – 6x – 6y + 14 = 0 and also touches the y-axis is given by the equation
  • a)
    x2 – 6x – 10y + 14 = 0 
  • b)
    x2 – 10x – 6y + 14 = 0
  • c)
    y2 – 6x – 10y + 14 = 0 
  • d)
    y2 – 10x – 6y+14 = 0
Correct answer is option 'D'. Can you explain this answer?

Hansa Sharma answered
let the center of the circle be (h,k) and since it touches the y-axis
Therefore, its radius will be h it touches the circle x2+y2−6x−6y+14=0 externally
Therefore, C1C2 = r1 + r2
⇒ [(h-3)2 + (k-3)2]½ = h+2
⇒ k2−10h−6k+14=0
⇒ y2−10x−6y+14=0

If the line 2x – y + λ = 0 is a diameter of the circle x2+y2+6x−6y+5 = 0 then λ =
  • a)
    6
  • b)
    9
  • c)
    3
  • d)
    12
Correct answer is option 'B'. Can you explain this answer?

Rajesh Gupta answered
x2 + y2 + 6x − 6y + 5 = 0
Center O = (-3, 3)
radius r = √{(-3)2 + (3)2 - 5} 
= √{9 + 9 - 5} 
= √13
Since diameter of the circle passes through the center of the circle.
So (-3, 3) satisfies the equation 2x – y + λ = 0
=> -3*2 - 3 + λ = 0
=> -6 - 3 + λ = 0
=> -9 + λ = 0
=> λ = 9

The locus of the vertices of the family of parabol as     [2006]
  • a)
  • b)
  • c)
  • d)
Correct answer is option 'A'. Can you explain this answer?

Rohit Jain answered
Given parabola is  
∴ Vertex of parabola is 
To find locus of this vertex,
 64xy = 105
which is the required locus.

Find the equation of the circle passing through (–2, 14) and concentric with the circle x2 + y2 - 6x - 4y -12 = 0 .
  • a)
    x2 + y2 - 6x - 4y -156 = 0
  • b)
    x2 + y2 - 6x + 4y -156 = 0
  • c)
    x2 + y2 - 6x + 4y + 156 = 0
  • d)
    x2 + y2 + 6x + 4y + 156 = 0
Correct answer is option 'A'. Can you explain this answer?

Abhay Mehta answered
To find the equation of the circle passing through the point (2, 14) and concentric with the given circle, we need to determine the center and the radius of the circle.

Here are the steps to find the equation of the circle:

1. Find the center of the given circle:
To find the center of the given circle, we need to rewrite the equation of the circle in the standard form, which is (x - h)^2 + (y - k)^2 = r^2, where (h, k) represents the center of the circle.

Given equation: x^2 + y^2 - 6x - 4y - 12 = 0

Rearrange the equation: x^2 - 6x + y^2 - 4y = 12

Complete the square for x terms:
(x^2 - 6x + 9) + y^2 - 4y = 12 + 9

Complete the square for y terms:
(x^2 - 6x + 9) + (y^2 - 4y + 4) = 12 + 9 + 4

Simplify:
(x - 3)^2 + (y - 2)^2 = 25

The center of the given circle is (3, 2).

2. Find the radius of the given circle:
The radius of the given circle is the square root of the constant term in the standard form equation. In this case, the radius is √25 = 5.

3. Find the equation of the circle concentric with the given circle and passing through the point (2, 14):
Since the new circle is concentric with the given circle, the center will be the same at (3, 2). The radius of the new circle will also be 5.

Using the standard form of the circle, the equation of the new circle is:
(x - 3)^2 + (y - 2)^2 = 5^2

Simplifying:
(x - 3)^2 + (y - 2)^2 = 25

Therefore, the equation of the circle passing through (2, 14) and concentric with the given circle is:
x^2 + y^2 - 6x - 4y - 156 = 0

Hence, the correct answer is option 'A'.

The equation of a circle which passes through the three points (3, 0) (1, –6), (4, –1) is
  • a)
    2x2 + 2y2 + 5x – 11y + 3 = 0
  • b)
    x2 + y2 – 5x + 11y – 3 = 0
  • c)
    x2 + y2 + 5x – 11y + 3 = 0
  • d)
    2x2 + 2y2 – 5x + 11y – 3 = 0
Correct answer is option 'D'. Can you explain this answer?

Pooja Shah answered
Gen equation of a circle is (x−h)2+(y−k)2=r2 (3,0),(1,−6),(4,−1) circle passes through these points
∴ These three points should satisfy the equation
of circle.
(3−h)2+k2=r2 ___ (I)
(1−h)2 +(−6−k)2 = r2(1−h)2+(6+k)2=r2  ___ (II)
From (I) & (II)
(3−h)2+k2 =(1−h)2+(6+k)2
9+h2−6h+k2 =1+h2 2h+36+k2+12k
9−6h=1−2h+36+12k
9−37=4h+12k
−28=4h+12k
h+3k=−7
h=−7−3k ___ (III)
(4−h)2+(−1−k)2=r2 ___ (IV)
From (I) & (IV)
(3−h)2+k2 = (4−h)2 +(1+k)2
9+h2 −6h+k2
 =16+h2 −8h+1+k2+2k
9−6h=17−8h+2k
9−17=−2h+2k
−8=−2h+2k
−h+k=−4
k=−4+h ___ (V)
Put (V) in (III)
h=−7−3(−4+h)
h=−7+12−3h
h=5/4,k=−11/4,r=170/16
Eq of circle: (x−5/4)2 +(y+11/4)2 =170/16
x2+25/16−10x/4+y2 +121/16+22y/4=170/16
Simplifying, we get 2x2+xy2−5x+11y−3=0

Chapter doubts & questions for Circle - Chapter-wise Tests for JEE Main & Advanced 2025 is part of JEE exam preparation. The chapters have been prepared according to the JEE exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for JEE 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

Chapter doubts & questions of Circle - Chapter-wise Tests for JEE Main & Advanced in English & Hindi are available as part of JEE exam. Download more important topics, notes, lectures and mock test series for JEE Exam by signing up for free.

Top Courses JEE

Related JEE Content