A. log 2

B. - log 2

C. 2 log2

D. 0

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

The tangents are drawn to the ellipse x^{2}/a^{2}+y^{2}/b^{2}=1 at point where it is intersected by the line lx+my+n=0. The point of intersection of tangents at these points is

If the lines 4x+3y-1=0,x-y+5=0 and kx+5y-3=0 are concurrent,then k is equal to