#2**+1 **

Each 2 pi is a trip around the circle and doesn't affect the answer.

15 pi/2 = 6 pi + 3pi/2 so tan(15pi/2) = tan(3pi/2) and that is undefined because sin(3pi/2) = -1

and cos(3pi/2) = 0

and (-1/0) is division by 0 and that is undefined.

killersteve27 Sep 20, 2019