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Math Help - Proving Multiple Angel Formulas

  1. #1
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    Proving Multiple Angel Formulas

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    cos^2(θ)-sin^2(θ)=2cos^2(θ)-1

    and

    cos^2(θ)-sin^2(θ)=1-2sin^2(θ)
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  2. #2
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    \cos^2(\theta)+\sin^2(\theta)=1

    Therefore

    \sin^2(\theta)=1-\cos^2(\theta)

    So in your problem

    \cos^2(\theta)-\sin^2(\theta)

    becomes

    \cos^2(\theta)-(1-\cos^2(\theta))

    2\cos^2(\theta)-1

    Use the same idea for the second problem.
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