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Math Help - two trig proofs

  1. #1
    Member rtblue's Avatar
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    two trig proofs

    Proof number one:

    prove that \displaystyle \frac{cosx-sinx}{\cos2x} = \frac{cosx+sinx}{1+\sin2x}

    Proof number two:

    prove that \displaystyle \frac{1+tanx}{1-tanx} = \frac{\cos2x}{1-sinx}

    Any help is appreciated!
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  2. #2
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    In Q1, try replacing cos 2x with cos^2 x - sin^2 x , factorise DOTS and cancel.
    Then start with RHS and replace sin 2x with 2 sinx cos x and think about what you could replace the 1 with.

    In Q2,
    get both sides in terms of sin x and cos x only
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