I wonder why you are trying to do these problems? You clearly do not understand what it is all about. Now it may be the fault may well be with a poor textbook and/or instructor.

Convert $\displaystyle 3.9243$ to a degree measure and see what you get.

Recall that $\displaystyle \2\pi$ converted to a degree measure is $\displaystyle 360^o$.

But the $\displaystyle \arctan$ returns a number not a degree measure.