Question:
The area of the base of a right circular cylinder is 616 cm2 and its height is 2.5 cm. Find the curved surface area of the cylinder.
Solution:
Given:
Area of the base of a right circular cylinder $=616 \mathrm{~cm}^{2}$
Height $=2.5 \mathrm{~cm}$
Let $r$ be the radius of the base of a right circular cylinder.
$\pi \mathrm{r}^{2}=616$
$\Rightarrow \mathrm{r}^{2}=616 \times \frac{7}{22}$
$\Rightarrow \mathrm{r}^{2}=196$
$\Rightarrow \mathrm{r}=14 \mathrm{~cm}$
Curved surface area of the right circular cylinder $=2 \pi \mathrm{rh}=2 \times \frac{22}{7} \times 14 \times 2.5=220 \mathrm{~cm}^{2}$