A. 1

B. 2

C. 3

D. 6

P(θ) and D(θ+π/2) are two points on the ellipse x^{2}/a^{2}+y^{2}/b^{2}=1. The locus of point of intersection of tangents at P and D to the ellipse is

If the variable line l_{1}(x-a)+y=0 and l_{2}(x+a)+y=0 are conjugate lines w. r. to the ellipse x^{2}/a^{2}+y^{2}/b^{2}=1. Then the locus of their point of intersection is

The locus of the poles w.r.t the ellipse x^{2}/a^{2}+y^{2}/b^{2}=1 of tangents to its auxiliary circle is

If the line lx+my=1 is a normal to the ellipse x^{2}/a^{2}+y^{2}/b^{2}=1 then a^{2}/l^{2}-b^{2}/m^{2}=1

The radius of the circle passing through the foci of the ellipse x^{2}/16+y^{2}/9=1 and having its center at (0, 3) is