Question

The height and base radius of a cone are $6cm$ and $8cm$ respectively. The curved surface area of the cone is:

• A. $14\pi {cm}^2$
• B. $60\pi {cm}^2$
• C. $80\pi {cm}^2$
• D. $48\pi {cm}^2$

Answer 1

The correct option is C $80\pi {cm}^2$

The slant height of the cone is given by
$l=\sqrt{h^2+r^2}$
$l=\sqrt{6^2+8^2}$
$l=\sqrt{100}$
$\Rightarrow l=10cm$

Hence, the curved surface area of the cone $=\pi rl$
$=\pi$ $\times$ 8 $\times$ 10
$=80\pi$ ${cm}^2$