∫(1-cosx)^2 dx
= ∫[1-2cosx + (cosx)^2] dx
= x - 2sinx +(1/2)∫ (1+cos2x)dx
= x - 2sinx +(1/2)[ x+ (1/2)sin2x ] + C
=(3/2)x -2sinx +(1/4)sin2x + C