Answer
b)
Work Step by Step
The formula $A=0.5r^2\theta$ requires the angles to be in radius.
$\theta$ is currently in degrees, so we need to multiply it by $\pi/180$ to obtain it in radius.
Hence here the area of the sector: $A=0.5r^2\theta=0.5\cdot9^2(40)\pi/180=9\pi$ square ft, thus the answer is b).
