Matematika

Pertanyaan

1. Lim x menuju phi/2 (cosec^2 x - cosec x . Cotan x) 2. Lim x menuju phi/2 ( cos 2x) / (x - phi/4)

1 Jawaban

  • 1. Sin^2 (a) / (-2a).(Tan a)
    =1.1 / (-2).1
    = -1/2

    2. (cos 2x-1) / (cos 4x-1) =
    (cos 2x-1) / (cos^2 2x - sin^2 2x - 1) =
    (cos 2x-1) / (cos^2 2x - 1 + cos^2 2x - 1) =
    (cos 2x-1) / 2(cos 2x - 1)(cos 2x + 1) = 1 / 2(cos 2x + 1) =
    1 / 2(cos 2.(phi/4) + 1) = 1 / 2 (0+1) = 1 / 2

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