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Thread: Trigonometric Functions

  1. #1
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    Smile Trigonometric Functions

    Find tan if 9sin^2 - cos^2 =7

    I have divided through with cos^2

    Giving me:

    9tan^2 - 1 = 7sec^2

    But I am unsure on how to proceed from there.

    The books answer gives it as: tan = 2
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  2. #2
    MHF Contributor
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    Re: Trigonometric Functions

    $\sec^2(\theta) = 1 + \tan^2(\theta)$

    make that substitution and then let $u=\tan(\theta)$

    solve the resulting quadratic in $u$ and substitute $\tan(\theta)$ back in.
    Thanks from KiaraG16
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