Question

Find the surface area of the cone in terms of π.

180π cm2


108π cm2


144π cm2


90π cm2

Answer 1

`144\pi {cm}^(2)`

Explanation:

The formula for the surface area of a cone is

`s = \pi {r}^(2) + \pi \: rs`

Plugging given values r=6cm and s=18cm we get 144cm².

Answer 2

`144\pi \: {cm}^(2)`

Explanation:

Given:

d (diameter) = 12 cm

l = 18 cm

Find: A (surface area) - ?

First, we have to find the radius:

`r = (1)/(2) * d = (1)/(2) * 12 = 6 \: cm`

Now, we can find the surface area:

`a(surface) = \pi {r}^(2) + \pi * r * l`

`a(surface) = \pi * {6}^(2) + \pi * 6 * 18 = 36\pi + 108\pi = 144\pi \: {cm}^(2)`