Question

The height and radius of cone are $4cm$ and $3cm$ respectively. Find the curved surface area of cone.

• A. $14\pi {cm}^2$
• B. $16\pi {cm}^2$
• C. $15\pi {cm}^2$
• D. $12\pi {cm}^2$

Answer 1

The correct option is C

$15\pi {cm}^2$

Slant height is given by
$l=\sqrt{h^2+r^2}$
$l=\sqrt{4^2+3^2}$
$l=\sqrt{25}$
$\Rightarrow l=5cm$

Hence, curved surface area of cone will be
$=\pi rl$
$=\pi$ $\times$3 $\times$ 5
$=15\pi$ ${cm}^2$