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Thread: Equation

  1. March 11th 2011, 10:19 AM #1
    Critter314
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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. March 11th 2011, 10:23 AM #2
    emakarov
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    Let's see, cos(2 * 0) + cos(0) = 2. Hmm...
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  3. March 11th 2011, 10:36 AM #3
    TheChaz
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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. March 11th 2011, 06:40 PM #4
    Prove It
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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. March 12th 2011, 03:54 PM #5
    TheChaz
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    Yeah, I said that already!
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