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Math Help - Huge trouble with trig equations

  1. #1
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    Huge trouble with trig equations

    Say we have 3sinx = -3 from -pi to pi, for example.

    x = sin^-1(-1)

    So it's negative in the bottom quadrants.

    If I go 90 from tan, it ends up at 270, and 90 from cos ends up at 360.

    The book has the answer as -pi/2, or -90. Is this expressing it in its original form as a negative or what? I'm just really confused. I can do the positive domains fine.

    Cheers.
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  2. #2
    MHF Contributor
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    Why are you doing anything with cosine or tangent?

    \sin\left(-\frac{\pi}{2}\right) = -1

    What else is there to consider?
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  3. #3
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    Oh well we have to solve for the domain using a unit circle.
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