trigonometry

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exact value of

cot[arccos(-2/3)]

  • trigonometry -

    cos(θ)=-2/3
    So θ is in the second or third quadrant. There is not enough information to be sure of which.

    adjacent = -2
    hypotenuse = 3
    opposite = ±√(3²-(-2)²)
    = ±√(5)

    Therefore
    cot(θ)
    =adjacent/opposite
    =-2/(±√(5))
    = ±(2/√(5))
    =±(2√(5)/5)

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