A. 3x2+3y2-14x+23y-15=0

B. x2+y2+2x-6y-6=0

C. x2+y2+16y-8=0

D. 4x2+4y2-15x-4=0

If x^{2}+y^{2}+2gx+2fy+9=0 represents a circle with centre (1, -3) then radius=

The number of common tangents to the two circles x^{2}+y^{2}-8x+2y=0 and x^{2}+y^{2}-2x-16y+25=0 is

From any point on the circle x^{2}+y^{2}=a^{2} tangents are drawn to the circle x^{2}+y^{2}=a^{2} sin^{2}θ. The angle between them is

If the tangent at P on the circle x^{2}+y^{2}=a^{2} cuts two parallel tangents of the circle at A and B then PA. PB=

If (1,2), (4, 3) are the limiting points of a coaxal system , then the equation of the circle in its conjugate system having minimum area is