cos 2x + 5 sin x + 2 = 0 Tentukan nilai x jika 0 ≤ x ≤ 360 tolong dijawab beserta caranya

cos nx = 1 - 2sin² n/2 x
cos 2x = 1 - 2sin² 2/2 x
cos 2x = 1 - 2sin² x

cos2x + 5sinx + 2 = 0
1 - 2sin²x + 5sinx + 2 = 0
-2sin²x + 5sinx + 3 = 0
2sin²x - 5sinx - 3 = 0
(2sinx + 1)(sinx - 3) = 0

sinx - 3 = 0
sinx = 3 (tidak memenuhi)

2sinx + 1 = 0
2sinx = -1
sinx = -1/2
x = 210˚ dan 310˚

Hp = { x | x = 210˚ /\ x = 310˚ }