Question

A rectangular sheet of paper, 44 cm × 20 cm, is rolled along its length to form a cylinder. Find the total surface area of the cylinder thus generated.

Answer 1

$$\begin{gathered} \mathrm{The}\mathrm{rectangular}\mathrm{sheet}\mathrm{of}\mathrm{paper}44\mathrm{cm}\times 20\mathrm{cm}\mathrm{is}\mathrm{rolled}\mathrm{along}\mathrm{its}\mathrm{length}\mathrm{to}\mathrm{form}\mathrm{a}\mathrm{cylinder}.\mathrm{The}\mathrm{height}\mathrm{of}\mathrm{the}\mathrm{cylinder}\mathrm{is}20\mathrm{cm}\mathrm{and}\mathrm{circumference}\mathrm{is}44\mathrm{cm}. \\ \mathrm{We}\mathrm{have}: \\ \mathrm{Height},h=20\mathrm{cm} \\ \mathrm{Circumference}=2\mathrm{\pi }r=44\mathrm{cm} \\ \therefore \mathrm{Total}\mathrm{surface}\mathrm{area}\mathrm{is}S=2\mathrm{\pi }rh \\ =44\times 20\mathrm{cm}² \\ =880\mathrm{cm}² \end{gathered}$$