himpunan penyelesaian cos2x - cosx - 2 = 0 untuk 0°

Trigonometri

cos 2x = 2cos^2x - 1

2cos^2 x - cos x - 3 = 0
(2cos x - 3)(cos x + 1) = 0
cos x = 3/ 2 (TM)
cos x = - 1
->> x = 180°

Hp = {180°}