The volume of a right circular cone is 
and its height is 12 cm. Find its slant height and its curved surface area.
Given,
h = 12 cm
Volume of the cone = 100π cm3
r2h = 100 × 3
r2 × 12 = 100 × 3
r2 = 
= 25
r = 5cm
Curved surface area = πrl
= π × 5 × 13
= (65π) cm2
3