The curved surface area of a hemisphere is $308 {\text{cm}}^2$. Find its radius. Take$\pi =\frac{22}{7}$.

Concept: Hemisphere is formed when a sphere is divided into two equal parts.

We know that the curved surface area of a hemisphere $=2\pi r^2$

$\Rightarrow 2\times \frac{22}{7}\times r^2=308$

$\Rightarrow r=7\text{cm}$

Hence, the radius of a hemisphere is $7\text{cm}$.