Question

The curved surface area of a cylinder is 1320 cm² and its base has diameter 21 cm. Find the height of the cylinder.

Answer 1

$$\begin{gathered} \mathrm{Let}h\mathrm{be}\mathrm{the}\mathrm{height}\mathrm{of}\mathrm{the}\mathrm{cylinder}. \\ \mathrm{Given}: \\ \mathrm{Curved}\mathrm{surface}\mathrm{area},S=1320{\mathrm{cm}}^2 \\ \mathrm{Diameter},d=21\mathrm{cm} \\ \mathrm{Radius},\mathit{}r=10.5 \\ \mathrm{S}=2\mathrm{\pi }rh \\ 1320=2\mathrm{\pi }\times 10.5\times h \\ \mathit{}\mathit{}h=\frac{1320}{2\mathrm{\pi }\times 10.5} \\ \mathit{}\mathit{}h=20\mathrm{cm} \end{gathered}$$