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

A. 30π m²

B. 40π m²

C. 60π m²

D. 80π m²

Answer: Option C

Solution(By Examveda Team)

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