Решить уравнение! cosx+cos5x+2sin^2x=1

1. 2sin^2x = 1 - cos2x
2.cosx + cos5x - cos2x = 0, 2cos3xcos2x - cos2x = 0, cos2x(2cos3x - 1) = 0
3.cos2x = 0, 2x = П/2 + Пк, х = П/4 + Пк/2
4.2cos3x - 1 = 0, cos3x = 1/2, 3x = +-П/3 + 2Пк, х = +-П/9 + 2Пк/3