cos 2x-3cosx+2=0, 0

TRIgonomeTRI

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

2cos x - 1 = 0
cos x = 1/2 ---> x = 60° ; x = 300°

cos x - 1 = 0
cos x = 1 ---> x = 0° ; x = 360°

Interval : 0° < x < 360°

Nilai x yg memenuhi :
60° dan 300°