Prove that cos6x + 6cos4x + 15cos2x + 10/cos5x + 5cos3x + 10cosx = 2cosx
Matematika
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Prove that cos6x + 6cos4x + 15cos2x + 10/cos5x + 5cos3x + 10cosx = 2cosx
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1. Jawaban Anonyme
Bab Trigonometri
Matematika SMA Kelas X
(cos 6x + 6 . cos 4x + 15 . cos 2x + 10) / (cos 5x + 5 . cos 3x + 10 cos x)
= (cos 6x + cos 4x + 5 cos 4x + 5 cos 2x + 10 cos 2x + 10) / (cos 5x + 5 . cos 3x + 10 cos x)
= ((cos 6x + cos 4x) + 5 (cos 4x + cos 2x) + 10 (cos 2x + 1)) / (cos 5x + 5 . cos 3x + 10 . cos x)
= (2 cos 5x cos x + 5 . 2 cos 3x cos x + 10 . 2 cos² x) / (cos 5x + 5 . cos 3x + 10 cos x)
= (2 cos x (cos 5x + 5 cos 3x + 10 cos x)) / (cos 5x + 5 cos 3x + 10 cos x)
= 2 cos x
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