Persamaan 2cos2 x-3 cosx + 1=

2cos^2 x -3cos x + 1 = 0
(2 cos x- 1)( cos x - 1) = 0
2 cos x - 1 = 0'atau cos x -1 = 0
2 cos x = 1
cos x = 1/2
cos x = cos 60, 300
cos x = 1
cos x = cos 0, 360
x = { 0, 60, 300, 360 }