Question

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

Answer 1



By rolling along the length, we get a cylinder whose circumference of its base $=44cm$

and, height $\left(h\right)=20cm$

Let ${}^{\prime }{r}^{\prime }$ be the radius.

then, Circumference of base $=44cm$

$\therefore 2\pi r=44$

$\Rightarrow 2\times \frac{22}{7}\times r=44$

$\Rightarrow r=\frac{44\times 7}{2\times 22}=7cm$

$\therefore$ Total surface area of the cyinder $=2\pi r(h+r)$

$=2\times \frac{22}{7}\times 7(20+7)=1188c{m}^2$