Question

Given a metal pipe $77\mathrm{cm}$ long and inner diameter is $4\mathrm{cm}$ and outer diameter is $4.4\mathrm{cm}$. Find the outer curved surface area of the pipe.

Answer 1

Find the curve surface area

Given: Height of pipe $=77\mathrm{cm}$ and outer diameter of the pipe $=4.4\mathrm{cm}$

The outer curved surface area of the pipe.

$$\begin{gathered} =(2\times \mathrm{\pi }\times (\mathrm{outer}\mathrm{radius})\times \mathrm{height})\mathbf{}[\because \mathrm{Curved}\mathrm{surface}\mathrm{area}\mathrm{of}\mathrm{cylinder}=2\mathrm{\pi rh}] \\ =2\times \mathrm{\pi }\times \frac{4.4}{2}\times 77[\because \mathrm{radius}=\frac{\mathrm{diameter}}{2}] \\ =2\times \mathrm{\pi }\times 2.2\times 77 \\ =1064.8{\mathrm{cm}}^2 \end{gathered}$$

Therefore outer curve surface area $\mathbf{=}\mathbf{}\mathbf{1064}\mathbf{.}\mathbf{8}\mathbf{}{\mathbf{cm}}^{\mathbf{2}}$