A. 4

B. 3

C. 1

D. 2

The locus of the middle points of portions of the tangents to the circle x^{2}+y^{2}=a^{2} terminated by the axes is

If the length of the tangets from two points A, B to a circles are 6, 7 respectively. If A, B are conjugate points then AB=

The length of the tangent from a point on the circle x^{2}+y^{2}+2gx+2fy+c=0 to the circle x^{2}+y^{2}+2gx+2fy+c^{’}=0 is

The normal of the circle(x-2)^{2}+(y-1)^{2}=16 which bisects the chord cut off by the line x-2y-3=0 is

The length of the common chord of the circles (x-a)^{2}+(y-b)^{2}=c^{2} and (x-b)^{2}+(y-a)^{2}=c^{2}