The slant height of a right circular cone is 10 m and its height is 8 m. Find the area of its curved surface.

Answer: Option C

$$\begin{array}{rl}& l=10m,h=8m\\ & So,\\ & r=\sqrt{l^2+h^2}\\ & =\sqrt{{\left(10\right)}^2-{\left(8\right)}^2}\\ & =6m\end{array}$$
∴ Curved surface area :
$$\begin{array}{rl}& =\pi rl\\ & =\left(\pi \times 6\times 10\right)m^2\\ & =60\pi m^2\end{array}$$