Selesaikanlah persaman COS2x-2SINX=-2COS2x+1

cos 2x - 2.sin x = -2.cos 2x + 1
cos 2x + 2.cos 2x - 2.sin x - 1 = 0
3.cos 2x - 2.sin x - 1 = 0
3(1 - 2.sin²x) - 2.sin x - 1 = 0
3 - 6.sin²x - 2.sin x - 1 = 0
-6.sin²x - 2.sin x + 2 = 0
bagi -2
3.sin²x + sin x - 1 = 0
sin x = {-1 ± √(1² - (4×3×-1))} / 2(3)
sin x = {-1 ± √13} / 6