A. 5

B. √85

C. √85/2

D. nonex

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}

The external centre of similitude of the two circles x^{2}+y^{2}-2x-6y+9=0, x^{2}+y^{2}=4 is

The longest distance from (-3, 2) to the circles x^{2}+y^{2}-2x+2y+1=0 is