Question

An open cone has a radius of 6cm and a height of 8cm . What is its surface area in square centimetre?

Answer 1

surface area of a cone = πrl, where l is the slant height, (the hypotenuse)

l^2 = r^2 + h^2, h being the height
l^2 = 6^2 + 8^2 = 36+64
l = 10

lateral surface area of cone = π(6)(10) cm^2
= 60π cm^2