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Math Help - Pathagorian identity

  1. #1
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    Pathagorian identity

    Write tanΘ in terms of sinΘ if the terminal side of Θ is in quadrant IV.

    So far I have cos^2Θ+sin^2Θ=1
    cosΘ=+/-sqrt(1-sin^2Θ)

    but this is as far as I can get?
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  2. #2
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    Cosine is positive in this quadrant, so you should be able to write \cos\theta=\sqrt{1-\sin^2\theta}. You can test this with an angel in IV.

    \tan\theta =\frac{\sin\theta}{\cos\theta} = \frac{\sin\theta}{\sqrt{1-\sin^2\theta}}
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  3. #3
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    Thanks! I've got it now.
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