Question

A closed cylindrical tank of radius $7m$and height $3m$is made from a sheet of metal how much sheet of metal is required

Answer 1

Total surface area of cylindrical tank $=2\pi r(h+r)$

$$\begin{gathered} =2\times (22/7)\times 7(3+7) \\ =44\times 10=440 \end{gathered}$$

Therefore, $440m^2$ metal sheet is required.