Question

The volume of a hemisphere is $2425\frac{1}{2}c{m}^3$. Find its curved surface area. $[Use\pi =\frac{22}{7}].$

Answer 1

$Volumeofhemisphere=\frac{2}{3}\pi r^3$

$\Rightarrow 2425\frac{1}{2}=\frac{2}{3}\pi r^3$

$\frac{4851}{2}=\frac{2}{3}\cdot \frac{22}{7}{r}^3$

$r^3=\frac{4851\times 3\times 7}{2\times 2\times 22}$

$r^3=\frac{441\times 21}{2\times 2\times 2\times 2}$

$\therefore r=\frac{21}{2}cm$

Curved Surface Area$=2\pi r^2$

$=2\times \frac{21}{2}\times \frac{21}{2}\times \frac{22}{7}$

$=693c{m}^2$