Dane:
V=27
P_b=2P_p
2\pi rh=2\pi r^2/:2\pi r
h=r
V=\pi r^2*h
\pi r^2h=27
\pi r^2*r=27
\pi r^3=27/:\pi
r^3=\frac{27}{\pi}
r=\sqrt[3]{\frac{27}{\pi }}=\frac{3}{\sqrt[3]{\pi} }
r=\frac{3}{\sqrt[3]\pi}*\frac{\sqrt[3]\pi*\sqrt[3]\pi}{\sqrt[3]\pi*\sqrt[3]\pi}=\frac{3\sqrt[3]{\pi^2}}{\pi}
h=r=\frac{3\sqrt[3]{\pi^2}}{\pi}
Można jeszcze podstawić za pi=3,14.
I wtedy będzie
h=r=\frac{3\sqrt[3]{3,14^2}}{3,14}\approx\frac{3*\sqrt[3]{9,86}}{3,14}\approx
\approx\frac{3*2,13}{3,14}\approx2,03