15. Locus of the point of intersection of two normals to the parabola y²=4ax which are at right angles to one another is

A) y²=a(x-2a)

B) y²=a(x+2a)

C) y²=a(x-3a)

D) y²=a(x+3a)

let the two ponits be (at1,2at1) and (at2,2at2).find the equation of normal and substitute these points and use the form of tanx.

tanx={(m1-m2)/(1+m1m2)}.

try and tell me .if you won't get it i will post the solution.