Circle PYQs - Last 5 Years

The locus of the third vertex of a right-angled triangle, the ends of whose hypotenuse are $(1,2)$ and $(4,5)$ is

If the lines $3 x-4 y+4=0$ and $6 x-8 y-7=0$ are the tangents to the same circle, then the area of that circle (in sq. units) is

A circle touches both the coordinate axes and the straight line $L \equiv 4 x+3 y-6=0$ in the first quadrant. If this circle lies below the line $L=0$, then the equation of that circle is

Circles are drawn through the point $(2,0)$ to cut intercepts of length 5 units on the $X$-axis. If their centre lie in the first quadrant, then their equation is

If the smallest circle through the points of intersection of $x^2+y^2=a^2$ and $x \cos \alpha+y \sin \alpha=p, 0

$A(4,3), B(2,5)$ are two points. If $P$ is a variable point on the same side as that of the origin with respect to the line $A B$ and is at most at a distance of 5 units from the mid-point of $A B$, then the locus of $P$ is

If the equation of the circle having the common chord to the circles $x^2+y^2+x-3 y-10=0$ and $x^2+y^2+2 x-y-20=0$ as its diameter is $x^2+y^2+\alpha x+\beta y+\gamma=0$, then $\alpha+2 \beta+\gamma=$

If $r_1$ and $r_2$ are radii of two circles touching all the four circles $(x \pm r)^2+(y \pm r)^2=r^2$, then $\frac{r_1+r_2}{r}=$

If the line $4 x-3 y+7=0$ touches the circle $x^2+y^2-6 x+4 y-12=0$ at $(\alpha, \beta)$, then $\alpha+2 \beta=$

The slope of the common tangent drawn to the circles $x^2+y^2-4 x+12 y-216=0$ and $x^2+y^2+6 x-12 y+36=0$ is

The circles $x^2+y^2-2 x-4 y-4=0$ and $x^2+y^2+2 x+4 y-11=0$

A circle passing through origin cuts the coordinate axes is $A$ and $B$. If the straight line $A B$ passes through a fixed point $\left(x_1, y_1\right)$, then the locus of the centre of the circle is

The equation of the circle touching the lines $|x-2|+|y-3|=4$ is

If $(\alpha, \beta)$ is the external centre of similitude of the circles $x^2+y^2=3$ and $x^2+y^2-2 x+4 y+4=0$, then $\frac{\beta}{\alpha}=$

If the chord joining the points $(1,2)$ and $(2,-1)$ on a circle subtends an angle of $\frac{\pi}{4}$ at any point on its circumference, then the equation of such a circle is

The equation of the circle which cuts all the three circles $4(x-1)^2+4(y-1)^2=1,4(x+1)^2+4(y-1)^2$ and $4(x+1)^2+4(y+1)^2=1$ orthogonally is

If $A(\cos \alpha, \sin \alpha), B(\sin \alpha,-\cos \alpha), C(1,2)$ are the vertices of a $\triangle A B C$, then the locus of its centroid is

$3 x+4 y-43=0$ is a tangent to the circle $S \equiv x^2+y^2-6 x+8 y+k=0$ at a point $P$. If $C$ is the centre of the circle and $Q$ is a point which divides $C P$ in the ratio $-1: 2$, then the power of the point $Q$ with respect to the cir...

$A(a, 0)$ is a fixed point and $\theta$ is a parameter such that $0<\theta<2 \pi$. If $P(a \cos \theta, a \sin \theta)$ is a point on the circle $x^2+y^2=a^2$ and $Q(b \sin \theta,-b \cos \theta)$ is a point on the circle $x^2+y^2=b^2$, the...

If $2 x-3 y+1=0$ is the equation of the polar of a point $P\left(x_1, y_1\right)$ with respect to the circle $x^2+y^2-2 x+4 y+3=0$, then $3 x_1-y_1=$

If a unit circle $S \equiv x^2+y^2+2 g x+2 f y+c=0$ touches the circle $S^{\prime} \equiv x^2+y^2-6 x+6 y+2=0$ externally at the point $(-1,-3)$, then $g+f+c=$

If the equation of the circle passing through the point $(8,8)$ and having the lines $x+2 y-2=0$ and $2 x+3 y-1=0$ as its diameters is $x^2+y^2+p x+q y+r=0$, then $p^2+q^2+r=$

If the radical axis of the circles $x^2+y^2+2 g x+2 f y+c=0$ and $2 x^2+2 y^2+3 x+8 y+2 c=0$ touches the circle $x^2+y^2+2 x+2 y+1=0$, then

If $\theta$ is the angle between the tangents drawn from the point $(-1,-1)$ to the circle $x^2+y^2-4 x-6 y+c=0$ and $\cos \theta=-\frac{7}{25}$, then the radius of the circle is

From a point $P(-4,0)$, two tangents are drawn to the circle $x^2+y^2-4 x-6 y-12=0$ touching the circle at $A$ and $B$. If the equation of the circle passing through $P, A$ and $B$ is $x^2+y^2+2 g x+2 f y+c=0$, then $(g, f)=$

If the power of the point $(1,6)$ with respect to the circle $x^2+y^2+4 x-6 y-a=0$ is -16 , then $a=$

The radius of the circle passing through the points of intersection of the circles $x^2+y^2+2 x+4 y+1=0$, $x^2+y^2-2 x-4 y-4=0$ and intersecting the circle $x^2+y^2=6$ orthogonally is

When the axes are rotated through an angle $\theta$ about origin in anti-clockwise direction and then translated to the new origin $(2,-2)$, if the transformed equation the equation of $x^2+y^2=4$ is $X^2+Y^2+a X+b Y+c=0$ then $a+b+c=$

If the equation of the polar of the point $(\alpha,-1)$ with respect to the circle $x^2+y^2-4 x-6 y-12=0$ is $y=\beta$, then $4(\alpha+\beta)=$

After the coordinate axes are rotated through an angle $\frac{\pi}{4}$ in the anti-clockwise direction without shifting the origin, if the equation $x^2+y^2-2 x-4 y-20=0$ transforms to $a x^2+2 h x y+b y^2+2 g x+2 f y+c=0$ in the new coordi...

If $P(\alpha, \beta)$ is the radical centre of the circles $S \equiv x^2+y^2+4 x+7=0, S^{\prime}=2 x^2+2 y^2+3 x+5 y+9=0$ and $S^{\prime \prime} \equiv x^2+y^2+y=0$, then the length of the tangent drawn from $P$ to $S^{\prime}=0$ is

The slope of one of the direct common tangents drawn to the circles $x^2+y^2-2 x+4 y+1=0$ and $x^2+y^2-4 x-2 y+4=0$ is

If the pole of the line $x+2 b y-5=0$ with respect to the circle $S \equiv x^2+y^2-4 x-6 y+4=0$ lies on the line $x+b y+1=0$, then the polar of the point $(b,-b)$ with respect to the circle $S=0$ is

If $(1, a),(b, 2)$ are conjugate points with respect to the circle $x^2+y^2=25$, then $4 a+2 b=$

If the circles $x^2+y^2+5 k x+2 y+k=0$ and $2 x^2+2 y^2+2 k x+3 y-1=0, k \in R$ intersect at points $P$ and $Q$ then the line $4 x+5 y-k=0$ passes through $P$ and $Q$ for

Length of the common chord of two circles of same radius is $2 \sqrt{17}$. If one of the two circles is $x^2+y^2+6 x+4 y-12=0$, then acute angle between the two circles is

If $Q$ is the inverse point of $P(-1,1)$ with respect to the circle $x^2+y^2-2 x+2 y=0$, then the line containing $Q$ is

Let $\theta$ be the angle between the circles $S \equiv x^2+y^2+2 x-2 y+c=0$ and $S^{\prime} \equiv x^2+y^2-6 x-8 y+9=0$. If $c$ is an integer and $\cos \theta=\frac{5}{16}$, then the radius of the circle $S=0$ is

A circle $S \equiv x^2+y^2-16=0$ intersects another circle $S^{\prime}=0$ of radius 5 units such that their common chord is of maximum length. If the slope of that chord is $\frac{3}{4}$, then the centre of such a circle $S^{\prime}=0$ is

If the circle passing through $(3,5),(5,5)$ and $(3,-3)$ cuts the circle $x^2+y^2+2 x+2 f y=0$ orthogonally, then $f=$

If the circles $x^2+y^2-2 \lambda x-2 y-7=0$ and $3\left(x^2+y^2\right)-8 x+29 y=0$ are orthogonal, then $\lambda=$

If the point of contact of the circles $x^2+y^2-6 x-4 y+9=0$ and $x^2+y^2+2 x+2 y-7=0$ is $(\alpha, \beta)$, then $7 \beta=$

If the equation of the circle lying in the first quadrant, touching both the coordinate axes and the line $\frac{x}{3}+\frac{y}{4}=1$ is $(x-c)^2+(y-c)^2=c^2$, then $c=$

If $\left(\frac{1}{10}, \frac{-1}{5}\right)$ is the inverse point of a point $(-1,2)$ with respect to the circle $x^2+y^2-2 x+4 y+c=0$ then $c=$

A circle passing through the point $(1,0)$ makes an intercept of length 4 units on $X$-axis and an intercept of length $2 \sqrt{11}$ units on $Y$-axis. If the centre of the circle lies in the fourth quadrant, then the radius of the circle i...

A circle touches the line $2 x+y-10=0$ at $(3,4)$ and passes through the point $(1,-2)$. Then, a point that lies on the circle is

The angle between the tangents drawn from the point $(2,2)$ to the circle $x^2+y^2+4 x+4 y+c=0$ is $\cos ^{-1}\left(\frac{7}{16}\right)$. If two such circles exist, then sum of the values of $c$ is

If a circle $S$ passes through the origin and makes an intercept of length 4 units on the line $x=2$, then the equation of the curve on which the centre of $S$ lies is

If $(a, b)$ is the common point for the circles $x^2+y^2-4 x+4 y-1=0$ and $x^2+y^2+2 x-4 y+1=0$, then $a^2+b^2=$

If the circle $S=x^2+y^2+2 g x+4 y+1=0$ bisects the circumference of the circle $x^2+y^2-2 x-3=0$, then the radius of circle $S=0$ is