Answer
$h=\dfrac{S}{2\pi r}-r$
Work Step by Step
$S=2\pi rh+2\pi r^{2}$ $,$ for $h$
Take $2\pi r^{2}$ to subtract the left side:
$S-2\pi r^{2}=2\pi rh$
Take $2\pi r$ to divide the left side:
$\dfrac{S-2\pi r^{2}}{2\pi r}=h$
Rearrange:
$h=\dfrac{S-2\pi r^{2}}{2\pi r}$
Simplify:
$h=\dfrac{S}{2\pi r}-r$
