Matematika

Pertanyaan

Jika cos p= akar 7/11 dan p sudut lancip maka tentukan nilai cot(360-p)-1 / cosec(180+p)

2 Jawaban

  • Materi : Trigonometri

    Pembahasan :
    Identitas Trigonometri
    Sin²p + Cos²p = 1
    Sin²p = 1 - Cos²p
    Sin²p = 1 - (√7/11)²
    Sin²p = 1 - 7/121
    Sin²p = 114/121
    Sin p = (√114)/11

    [Cot (360° - p) - 1]/[Cosec (180° + p)]
    = [- Cot p - 1]/[- 1/Sin p]
    = [Cot p + 1]/[1/Sin p]
    = Sin p . Cot p + Sin p
    = Sin p . Cos p / Sin p + Sin p
    = Cos p + Sin p
    = (√7)/11 + (√114)/11
    = (√141 + √7)/11
  • cos p = √7 /11
    sin p = √(1 - cos² p)
    sin p = √(1 - (7/121))
    sin p = √((121 - 7)/121)
    sin p = (1/11)√114

    (cot (360° - p) - 1) / (cosec (180° + p))
    = (-cot p - 1) / (- cosec p)
    = -(cot p + 1)/(-1/sin p)
    = sin p (cos p/sin p + 1)
    = cos p + sin p
    = √11 /11 + √114 /11
    = (1/11)(√11 + √114)

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