
Mark H. answered 05/09/19
Tutoring in Math and Science at all levels
This is the inverse of the chain rule for differentiation:
d/dx g ( f(x) ) = g' (f(x) * f'(x)
For g, integrate 1-cos(x) to get x - sin(x) + C
For f, it is simply the integral of g^2, which is g^3 / 3 + D
So, the complete integral is ( x - sin(x) + C )^3 ) / 3 + D
Differentiate this to confirm you get the original equation