Answer:
[tex]r=\sqrt{\frac{V}{nh} }[/tex]
Step-by-step explanation:
[tex]V=nr^{2}h\\\frac{V}{nh}=\frac{nr^{2}h }{nh}\\\frac{V}{nh}=r^{2}\\\sqrt{\frac{V}{nh} }=\sqrt{r^{2} }\\r=\sqrt{\frac{V}{nh} }[/tex]