Question

A metal pipe is $77cm$ long. The inner diameter of a cross-section is $4cm$, the outer diameter being $4.4cm$, then find its inner curved surface area.

Answer 1

Dimensions be :

$\Rightarrow R=$ outer radius $=\frac{4.4}{2}=2.2cm$

$r=$ Inner radius $=\frac{4}{2}=2cm$

$\Rightarrow$ Height $h=77cm$

$\therefore$ Outer curved surface area $=2\pi rh$

$=2\times \frac{22}{7}\times 2\times 77$

$=968c{m}^2$

$\therefore$ Outer curved surface area $=968c{m}^2.$

Hence, the answer is $968c{m}^2.$