tentukan himpunan oenyekesaian dari cos 2x + sin x = 0

cos2x + sinx = 0
1 - 2 sin²x + sinx = 0
2sin²x - sinx - 1 = 0
(2sinx + 1) (sinx - 1) = 0

(i)
2sinx + 1 = 0
2sinx = -1
sinx = -1/2
x = 210° , 330°

(ii)
sinx - 1 = 0
sinx = 1
x = 90°

HP = {90° , 210° , 330°}