c)
r=2a
V_{bryly}=V_{walca}+2*V_{stozka}=
=\pi r^2*\frac{1}{3}h+2*\frac{1}{3}*\pi r^2*\frac{1}{3}h=
=\pi *4a^2*\frac{1}{3}h+\frac{2}{3}\pi 4a^2*\frac{1}{3}h=
=\frac{4}{3}\pi a^2h+\frac{8}{9}\pi a^2h=\frac{12}{9}\pi a^2h+\frac{8}{9}\pi a^2h=\frac{20}{9}\pi a^2h=
=2\frac{2}{9}a^2h\pi(j^3)