Cos 2x + 5 sin x + 2 = 0Tentukan nilai x jika 0 ≤ x ≤ 360tolong dijawab beserta caranya
Jawaban Terkonfirmasi
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˚ }