A right circular cone whose base diameter is equal to its altitude.?

Question

It is circumscribed about a right circular cylinder of base radius 6 cm. and altitude 14 cm. Find the lateral area of the cone.

Answer 1

C = h = 20
L^2 = 400 + 100/π^2
A = πL^2(C/2πL) =
20π(400 + 100/π^2)/(2π√(400 + 100/π^2)) =
10√(400 + 100/π^2) =
50√(4 + 1/π^2) ≈ 101.2586 cm^2 ≈ 101 cm^2