Answer
$13.96\text{ in}$
Work Step by Step
Here, $r$ denotes the radius of the sector of the circle.
The Arc Length $s$ can be computed using the formula
$s=r\cdot \frac{\theta}{180}\cdot \pi$
where $\theta$ is in degrees.
Use the formula above to obtain
$s=40\cdot \frac{20}{180}\cdot \pi\approx13.96\text{ in}$.