Find the area of a 120° sector of a circle whose radius is 6.

First, determine the area of the whole circle by the equation, A = πr². Substituting,
                             A = π(6²) = 36π
Then, multiply this value with the ratio of the given angle to the whole revolution,
                            A(sector) = 36π x (120° / 360°)
The area of the sector is therefore 12π units².