Question

Harga x yang memenuhi persamaan + cosx - 2= 0 untuk 0≤x≤360 adalah....

Answer 1

2 sin² x + √3 cos x - 2 = 0
2(1 - cos² x) + √3 cos x - 2 = 0
2 - 2 cos² x + √3 cos x - 2 = 0
- 2 cos² x + √3 cos x = 0
cos x( -2 cos x + √3) = 0
cos x = 0 atau -2 cos x + √3 = 0

# cos x = 0
cos x = cos 90
x = 90 + k.360
atau
x = -90 + k.360
k = 0, x = -90, 90
k = 1, x = 450, 270

# -2 cos x + √3 = 0
-2 cos x = -√3
cos x = √3/2
cos x = cos 30
x = 30 + k.360
atau
x = -30 + k,360
k = 0, x = -30, 30
k = 1, x = 390, 330

HP : {30, 90, 270, 330}