The lateral surface area of frustum of a right circular cone if the area of its base is 16π cm2 and the diameter of circular upper surface is 4 cm and slant height 6 cm, will be

Answer: Option C

Base Area = 16π
πR² = 16π
R = 4
Given r = 2
∵ ΔABC ≅ ΔADE
$$\begin{array}{rl}& \therefore \frac{\text{BC}}{\text{DE}}=\frac{\text{AC}}{\text{AE}}\\ & \frac{4}{8}=\frac{6}{\text{AE}}\\ & \text{AE}=12=\text{L}\end{array}$$
Surface Area of frustum
= πRL - πr$$l$$
= π × 4 × 12 - π × 2 × 6
= 48π - 12π
= 36π