Question

Curved surface area of a cone is $308$m${}^2$ and its slant height is $14$cm. Find (i) radius of the base and (ii) total surface area of the cone.

Answer 1

Given, $l=14$cm.

Let $x$ be radius of cone
CSA of cone $=\pi rl=\pi xl$
$3.0=\pi xl$
$x=\frac{308}{\frac{22}{7}\times 14}=7$cm
Total Surface Area $=$ CSA $+$ Area of base
$=308+\pi r^2$
$=308+\frac{22}{7}\times 7\times 7$
$=308+154$
$=462$cm${}^2$