hp dari 4 sin x = 1 + 2 cos 2x

04 sin x = 1 + 2cos 2x
4 sin x = 1 + 2(1 - 2.sin²x)
4.sin x = 1 + 2 - 4.sin²x
4.sin²x + 4.sin x - 3 = 0
(2.sin x - 1)(2.sin x + 3) = 0
2.sin x - 1 = 0
2.sin x = 1
sin x = ½
sin x = sin 30
x = 30°
sin x = sin 150
x = 150°
2.sin x + 3 = 0
2.sin x = -3
sin x = -3/2 (tidak memenuhi)