Let $C$ be a circle passing through the points $A (2,-1)$ and $B (3,4)$. The line segment $AB$ is not a diameter of $C$. If $r$ is the radius of $C$ and its centre lies on the circle $(x-5)^{2}+(y-1)^{2}=\frac{13}{2}$, then $r^{2}$ is equal to
$32$
$\frac{65}{2}$
$\frac{61}{2}$
$30$
The equation of radical axis of the circles ${x^2} + {y^2} + x - y + 2 = 0$ and $3{x^2} + 3{y^2} - 4x - 12 = 0,$ is
The number of circles touching the line $y - x = 0$ and the $y$-axis is
Two circles whose radii are equal to $4$ and $8$ intersects at right angles. The length of their common chord is:-
The radical axis of two circles and the line joining their centres are
The radical centre of three circles described on the three sides of a triangle as diameter is