A. A.P

B. G.P

C. H.P

D. none

If α, β are the roots of x^{2}+ ax+b=0 and γ, δ are the roots y^{2}+cx+d=0 then the equation of the circle having the line joining (α, γ), (β, δ) as diameter is

The least distance of the line 8x-4y+73=0 from the circle 16x^{2}+16y^{2}+48x-8y-43=0 is

The equation of the circle with centre (-1, 1) and touching the circle x^{2}+y^{2}-4x+6y-3=0 externally is

The orthocentre of triangle formed by the lines x + 3y = 10 and 6x<sup>2</sup> + xy - y<sup>2</sup> = 0 is:

B and C are two points on the circle x^{2}+y^{2}=a^{2}. From a point A(b, c) on that circle AB=AC=d. The equation to Bc is