Answer
$V=\displaystyle \frac{\pi}{3}(r^{2}h).$
Work Step by Step
If $V$ varies jointly with $r^{2}$ and $h , $
there exists a nonzero number $k$ such that
$V=k(r^{2}h).$
Given $k=\displaystyle \frac{\pi}{3},$ we write
$V=\displaystyle \frac{\pi}{3}(r^{2}h).$
