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Math Help - Equation

  1. #1
    Newbie Critter314's Avatar
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    Equation

    How to prove?
    cos 2x + cos x = sin^2 x
    All Ive got so far is cos^2 x - sin^2 x + cos x = sin^2 x
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  2. #2
    MHF Contributor
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    Let's see, cos(2 * 0) + cos(0) = 2. Hmm...
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  3. #3
    Super Member TheChaz's Avatar
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    It should read "solve", and we've already addressed this (7 minutes ago) at mymathforum!

    I'm ok with you replying in either place... Obviously
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  4. #4
    MHF Contributor
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    Now substitute \displaystyle \sin^2{x} = 1 - \cos^2{x} to get a quadratic equation in \displaystyle \cos{x}, which you will be able to solve.
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  5. #5
    Super Member TheChaz's Avatar
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    Yeah, I said that already!
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