Question

A solid cylinder of radius r and height h is placed over other cylinder of same height and radius. The total surface area of the shape so formed is _______.

Answer 1

Total height of the new cylinder, H = h + h = 2h

Radius of the new cylinder = r

∴ Total surface area of the shape (or new cylinder)

$$\begin{gathered} =2\mathrm{\pi }rH+2\mathrm{\pi }{r}^2 \\ =2\mathrm{\pi }r\left(H+r\right) \\ =2\mathrm{\pi }r\left(2h+r\right) \end{gathered}$$

A solid cylinder of radius r and height h is placed over other cylinder of same height and radius. The total surface area of the shape so formed is $\underline{2\mathrm{\pi }r\left(2h+r\right)}$.