pers cos 2x + sin x = 0 untuk x

Cos 2x + sin x = 0
1 - 2sin² x + sin x = 0
2sin² x - sin x - 1 = 0
(2sinx + 1) (sin x - 1) = 0
sin x = -½ V sin x = 1

Sin x = -½
x ={210°, 330} atau {7/6π, 11/6π}

Sin x = 1
x = {90°} atau {π/2}

Hp {π/2, 7/6π, 11/6π}