Question

The normals at three points P, Q, R of the parabola $y^2=4ax$ meet in (h, k). The centroid of triangle PQR lies on

• A. $x=0$
• B. $y=0$
• C. $x=-a$
• D. $y=a$

Answer 1

The correct option is B $y=0$

$y^2=4ax.............\left(1\right)$

Normals are drawn on $P,Q,R$ but from $(h,k)$

We know that centroid of triangle formed joining fleet of normals drawn from a point always lies on the axis of parabola. So, $(h,k)$ lies on axis of Parabola $y^2=4ax$ ie.

$=>y=0.$