Answer
$R=2\sqrt{(d-h)h}$
Work Step by Step
We know that the velocity is given as
$v=\sqrt{2g(d-h)}$
The time taken by water stream is given as
$t=\sqrt{\frac{2g}{h}}$
Now $R=vt$
$\implies R=(\sqrt{2g(d-h)})(\sqrt{\frac{2h}{g}})$
This simplifies to:
$R=2\sqrt{(d-h)h}$
