# Find the coordinate of double ordinate of parabola $y^2=4ax$?

$\begin{array}{1 1}(a)\;(h,2\sqrt{ah}),(h,-2\sqrt{ah})\\(b)\;(h,\sqrt{ah}),(h,-\sqrt{ah})\\(c)\;(h,3\sqrt{ah}),(h,-3\sqrt{ah})\\(d)\;(h,4\sqrt{ah}),(h,-4\sqrt{ah})\end{array}$

Let the abscissa of A be h hence ordinate of A,
$y^2=4ah$
$y=2\sqrt{ah}$(for first quadrant)
Hence co-ordinate of A and A' are $(h,2\sqrt{ah})$ and $(h,-2\sqrt{ah})$ respectively.
Hence (a) is the correct answer.