tan(3*pi) /-pi \ ---------*cos(3*pi) cot(a)*tan|----|*sin(pi) 4 \ 6 / ------------------- + ------------------------ 4 6
-1.32400117966243e-18 - 1.10104328370139e-18*cot(a)
___ cos(3*pi)*tan(3*pi) \/ 3 *cot(a)*sin(pi) ------------------- - -------------------- 16 18