Matematika

Pertanyaan

Buktikanlah identitas trigonometri berikut cos^4 x (1-tan^4 x) = cos^2x - sin^2x

1 Jawaban

  • Kelas 11 Matematika
    Bab Trigonometri Lanjut

    ^ = pangkat

    cos^4 x . (1 - tan^4 . x)
    = cos^4 x - cos^4 x . tan^4 x
    = cos^4 x - (cos^4 x . sin^4 . x/cos^4 x)
    = cos^4 x - sin^4 x
    = (cos² x + sin² x) . (cos² x - sin² x)
    = 1 . (cos² x - sin² x)
    = cos² x - sin² x

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