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Math Help - Find tan3x in terms of tanx.

  1. #1
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    Find tan3x in terms of tanx.

    Find tan3x in terms of tanx.

    Not sure where my starting point is?

    Thanks.
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  2. #2
    MHF Contributor

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    Start with the formula for tan(a+ b)= \frac{tan(a)+ tan(b)}{1+ tan(a)tan(b)}. Use that to find a formula for tan(2x) and then use tan(3x)= tan(2x+ x).
    Last edited by mr fantastic; March 1st 2009 at 06:16 PM. Reason: Fixed some latex, deleted comments about original thread title (there's a new title now ....)
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