Answer
$\approx 1.56$
Work Step by Step
RECALL:
The following are the means on how to find the reference angle of an angle $\theta$ based on its position:
(1) Quadrant I: $\theta$ (itself)
(2) Quadrant II: $\pi-\theta$
(3) Quadrant III: $\theta - \pi$
(4) Quadrant IV: $2\pi-\theta$
The angle $\theta = 4.7$ is between $\pi\approx 3.14$ and $\frac{3\pi}{2}\approx 4.71$. This means that the angle is in Quadrant III.
Use formula (3) to obtain:
reference angle of $4.7$ = $4.7 - \pi \approx 1.56$
