/ ________ ________\ 2 | / 2 / 2 | x *atan\\/ x - 1 - \/ x - 1 /
x^2*atan(sqrt(x^2 - 1) - sqrt(x^2 - 1))
/ ________ ________\ | / 2 / 2 | 2*x*atan\\/ x - 1 - \/ x - 1 /
0