Question

Tentukan himpunan penyelesaiannya!
15 cos²x + 1 - 4 cos x = 4 cos x, 0 ≤ x ≤ 360

Answer 1

Verified answer

TriGonoMetRi

15 cos² x + 1 - 4 cos x = 4 cos x
15 cos² x - 8 cos x + 1 = 0
(3 cos x - 1)(5 cos x - 1) = 0

Interval : 0° ≤ x ≤ 360°

Pembuat nol :
•
3 cos x - 1 = 0
cos x = 1/3
x = 70,53° atau x = 360° - 70,53° = 289,47°

•
5 cos x - 1 = 0
cos x = 1/5
x = 78,46° atau x = 360° - 78,46 = 281,54°

HP = {70,53° , 78,46° , 281,54° , 288,54°}