Answer:
[tex]r=\sqrt{R^2-\dfrac{V}{\pi h}}[/tex]
Step-by-step explanation:
You are being asked to solve the volume equation for r. We find that r is squared, added to something, the sum is multiplied by something. We want to undo those operations, in reverse order.
[tex]V=\pi h(R^2-r^2)\\\\\dfrac{V}{\pi h}=R^2-r^2\qquad\text{divide by $\pi h$}\\\\r^2=R^2-\dfrac{V}{\pi h}\qquad\text{add $r^2-V/(\pi h)$}\\\\\boxed{r=\sqrt{R^2-\dfrac{V}{\pi h}}}\qquad\text{square root}[/tex]
