Question

For a right circular cylinder of base radius = 7 cm and height = 14 cm, which is false?
(a) Curved surface area = 616 cm².
(b) Total surface area = 924 cm².
(c) Volume = 2156 cm³.
(d) Total area of the end faces = 154 cm².

Answer 1

(d) Total area of the end faces = 154 cm²

$$\begin{gathered} \left(\mathrm{a}\right)\mathrm{CSA}\mathrm{of}\mathrm{the}\mathrm{cylinder}=2\mathrm{\pi }rh\mathit{=}2\times \frac{22}{7}\times 7\times 14=616{\mathrm{cm}}^2 \\ \left(\mathrm{b}\right)\mathrm{Total}\mathrm{surface}\mathrm{area}\mathrm{of}\mathrm{the}\mathrm{cylinder}=2\mathrm{\pi }r\mathit{(}h+r\mathit{)}=2\times \frac{22}{7}\times 7\times (14+7)=1232{\mathrm{cm}}^2 \\ \left(\mathrm{c}\right)\mathrm{Volume}\mathrm{of}\mathrm{the}\mathrm{cylinder}=\mathrm{\pi }{r}^{\mathit{2}}\mathit{}h=\frac{22}{7}\times 7^2\times 14=2156{\mathrm{cm}}^2 \end{gathered}$$

$$\begin{gathered} \left(\mathrm{d}\right)\mathrm{Total}\mathrm{area}\mathrm{of}\mathrm{end}\mathrm{faces}=\mathrm{\pi }{r}^2+\mathrm{\pi }{r}^2 \\ =2\times \frac{22}{7}\times 7\times 7 \\ =44\times 7 \\ =308{\mathrm{cm}}^2 \end{gathered}$$
Hence, (d) is false.