Question

Find the reference angle to 5 pi and full in the calculations.

Answer 1

The angle given is in the second quadrant, this comes from the fact that is more than pi/2 but less than pi.

Then the reference angle is given by:

$\alpha=\pi-\frac{5\pi}{8}$

And the angles is:

$\alpha=\frac{3\pi}{8}$