Question

The outer diameter of a metallic pipe is $18$ cm and the thickness of the pipe is $2$ cm and the height is $4$ cm. Find the surface area of the metallic pipe.

Answer 1

Given:
Thickness $=2$ cm
Outer diameter of metallic pipe $=18$ cm

$\therefore$ Outer radius $\left(R\right)$$=9$ cm

Then inner radius $=9-2=7$ cm

Height of pipe $=4$ cm [Given]

The surface area of outer pipe $=2\pi Rh$

$=2\pi \times 9\times 4$

$=72\pi c{m}^2$

Inner surface area of pipe $=2\pi rh$

$=2\times \pi \times 7\times 4$

$=56\pi c{m}^2$

Hence, surface area of metallic pipe $=72\pi -56\pi$

$=16\pi c{m}^2$