acos(2*t)
d --(acos(2*t)) dt
-2 ------------- __________ / 2 \/ 1 - 4*t
-8*t ------------- 3/2 / 2\ \1 - 4*t /
/ 2 \ | 12*t | -8*|1 + --------| | 2| \ 1 - 4*t / ----------------- 3/2 / 2\ \1 - 4*t /