solve a=2pir^2 2pirh for pi
a = 2\(\pi\) \(r^{2}\) 2\(\pi\)rh |Divide by 4h\(r^{3}\)\(\pi ^{2}\) = \(\frac{a}{4h r^{3} }\) |Square root on both sides\(\pi\) = \(\sqrt{ \frac{a}{4h r^{3} } }\)
