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Math Help - Cosine graphing....?

  1. #1
    Junior Member Bartimaeus's Avatar
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    Exclamation Cosine graphing....?

    How do you graph cos^2 x?
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  2. #2
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    Quote Originally Posted by Bartimaeus View Post
    How do you graph cos^2 x?
    [we use a TI-84+ in school so that's easier...]

    There are several substitution formulas:

    cos^2 x + sin^2 x = 1
    2cos^2 x - 1 = cos2 x
    1 - 2sin^2 x = cos2x
    cos^2 x - sin^2 x = cos2x

    If you use the second one you get
    2cos^2 x - 1 = cos2 x
    2cos^2 x = 1 + cos2x
    cos^2 x = 1/2 + 1/2 cos2x

    so the problem changed to how do you draw the graph of 1/2 + 1/2cos2x
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  3. #3
    Junior Member Bartimaeus's Avatar
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    Ah ha! Wow, that is remarkably ... simple.
    Darn trigonometric identities, grr....

    Thanks!!!
    Last edited by mr fantastic; December 26th 2008 at 03:31 AM. Reason: Substituted darn for a potentially offensive word
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