>>56,66
>67 に従って
　{sin(x/3) - 2cos(x/3)}^2 = {sin(x/3)}^2 -4sin(x/3)cos(x/3) + 4{cos(x/3)}^2
　= (5/2) - 2sin(2x/3) + (3/2)cos(2x/3).

∫{sin(x/3) - 2cos(x/3)}^2 dx = (5/2)x + 3cos(2x/3) + (9/4)sin(2x/3) +c.