A. 1

B. 2

C. 3

D. 4

If (2, 6) is a centre of similitude for the-circles x^{2}+y^{2}=4 and x^{2}+y^{2}-2x-6y+9=0, the length of the common tangent of circles through it is

The radical axis of co-axial system of circle with the limiting points (1, 2) and (4, 3) is given by in equation

A tangent at a point on the circle x^{2}+y^{2}=a^{2 }intersects a concentric circle S at P and Q. The tangents to S at P and Q meet on the circle x^{2}+y^{2}=b^{2}. The equation to the circle S is

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

The equation of the circle cutting orthogonally circles x^{2}+y^{2}-4x+3y-1=0 and passing through the points (-2, 5), (0, 0) is