Jika 3 cos² 2x+4 cos 2x-4 =0, nilai nilai cos x =
Matematika
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Pertanyaan
Jika 3 cos² 2x+4 cos 2x-4 =0, nilai nilai cos x =
1 Jawaban
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1. Jawaban Anonyme
TriGonoMetRi
3cos² 2x + 4 cos 2x - 4 = 0
(3cos 2x - 2)(cos 2x + 2) = 0
cos 2x = 2/3 atau cos 2x = -2 (tdk memenuhi)
cos 2x = 2/3
2 cos² x - 1 = 2/3
2 cos² x = 1 + 2/3
cos² x = 5/(2.3)
cos x = √(5/6)
cos x = 1/6 √30
atau
cos x = -1/6 √30