Matematika

Pertanyaan

Prove that cos6x + 6cos4x + 15cos2x + 10/cos5x + 5cos3x + 10cosx = 2cosx

1 Jawaban

  • 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

    terbukti

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