Answer
$8$ square in.
Work Step by Step
The formula $A=0.5r^2\theta$ requires the angles to be in radius. $s=r\theta$ is the arc length. Thus $A=0.5s^2/\theta$ is another formula for $A$.
Hence here the area of the sector: $A=0.5s^2/\theta=0.5\cdot8^2/(4)=8$ square in.