trig

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If tan A = 2 and A belongs to [pie,3pie/2] then the expression cos A divided by sin cubed A +cos cubed A is equal to what?

  • trig -

    tanA = 2 in QIII means
    sinA = -2/√5
    cosA = -1/√5

    cosA/(sin^3A + cos^3A)
    = -1/√5 / (-8/5√5 - 1/5√5)
    = -1/√5 / (-9/5√5)
    = -1/√5 * -5√5/9
    = 5/9

    that's PI, not PIE!

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