A. a2-b2

B. a2+b2

C. (a2+b2)2

D. (a2-b2)2

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

If x and y are strictly positive such that x+y =1,then the minimum value of x log x + y log y is

The locus of middle point of the chord of the ellipse x^{2}/a^{2}+y^{2}/b^{2}=1 touching the ellipse The locus of midpoint of the chord of the ellipse x^{2}/α^{2}+y^{2}/β^{2}=1

The points on the ellipse x^{2}/25+y^{2}/9=1 whose angles differ by a right angle are

The chord of contact of tangents drawn from points on x^{2}/a^{2}+y^{2}/b^{2}=1 to the circle x^{2}+ y^{2}=c^{2 }touches the ellipse