=1/2∫x²(1-cos2x)dx=x³/6-1/4∫x²dsin2x=π³/6-x²sin2x/4+1/4∫sin2xdx²=π³/6-1/4∫xdcos2x=π³/6-xcos2x/4+sin2x/8=π³/6-π/4
