/ 2 \ acos\x - 1/
acos(x^2 - 1)
-2*x ------------------- _______________ / 2 / / 2 \ \/ 1 - \x - 1/
/ 2 / 2\\ | 2*x *\-1 + x /| -2*|1 + --------------| | 2| | / 2\ | \ 1 - \-1 + x / / ----------------------- ________________ / 2 / / 2\ \/ 1 - \-1 + x /
/ 2\ | 2 / 2\ | | 2 6*x *\-1 + x / | -4*x*|-3 + 5*x + ---------------| | 2| | / 2\ | \ 1 - \-1 + x / / ---------------------------------- 3/2 / 2\ | / 2\ | \1 - \-1 + x / /