A. x2+y2-r2-2p(x cos α+ y sinα-p)=0

B. x2+y2-r2+2p(x cos α+ y sinα-p)=0

C. x2+y2-r2-p(x cos α+ y sinα-p)=0

D. x2+y2-r2+p(x cos α+ y sinα-p)=0

The internal centre of similitude of the two circles x^{2}+y^{2}+6x-2y+1=0, x^{2}+y^{2}-2x-6y+9=0 is

If the line x+y+1=0 touches the circle x^{2}+y^{2}-3x+7y+14=0, then the point of contact is

The equation of the tangents to a circle x^{2}+y^{2}-4x-6y-12=0 and parallel to 4x-3y=1 are

Equation x^{2}+2ax-b^{2}=0 has real roots α, β and equation x^{2}+2px-q^{2}=0 has real roots γ, δ. If circle C is drawn with the points (α, γ), (β, δ) as extremities of a diameter, then the equation of C is

The equation of the circle passing through (0, 0) and cutting orthogonally the circles x^{2}+y^{2}+6x-15=0, x^{2}+y^{2}-8x+10=0 is