Find an exact value. Use double or half angle identity
I know that 13pi/12 is in quadrant three and tangent is positive.
I was stuck from the beginning. With the 13pi/12, because it wasn't on the unit circle. So i thought maybe if i turn it into degrees, then i didnt know how to really do that. And i tried thinking of ways to split it, but i only knew how to do it with cosine and sine ones.