I would convert to degrees first seems to make it easier.

×

= -468
by adding 360 twice we get the coterminal angle 252
252 is in the 3rd quadrant so 180 is the closest angle on the x-axis
ref angle = 252 - 180 = 72
If necessary convert back to radians...
The answer is on the picture below
15 is the answer i divided
Answer:
38.3
Step-by-step explanation:
hope I helped