## Thomas' Calculus 13th Edition

The angle is $\frac{5}{4}\pi rad$ or $225^\circ$
$r=8$ $s=10\pi$ $s=r\theta$ $\theta = \frac{s}{r}= \frac{10\pi}{8} = \frac{5}{4}\pi rad$ $\theta= \frac{5}{4}\pi rad = \frac{5}{4}180^\circ = 225^\circ$