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Math Help - Integration question

  1. #1
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    Integration question

    Hi, how do I integrate this?

    Int 1/(1 + cos 2x) dx

    Thanks
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by chancey View Post
    Hi, how do I integrate this?

    Int 1/(1 + cos 2x) dx

    Thanks
    remember, \cos 2x = 2 \cos^2 x - 1
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  3. #3
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    Yeah, but I still can't solve it with that?
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  4. #4
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by chancey View Post
    Hi, how do I integrate this?

    Int 1/(1 + cos 2x) dx

    Thanks
    Quote Originally Posted by Jhevon View Post
    remember, \cos 2x = 2 \cos^2 x - 1
    What he's up to is
    \int \frac{dx}{1 + cos(2x)} = \int \frac{dx}{1 + 2cos^2(x) - 1} = \int \frac{dx}{2cos^2(x)}

    = \frac{1}{2} \int sec^2(x) dx

    Do you know of any function who's derivative is sec^2(x)?

    -Dan

    Edit: Jhevon politely and quietly PMed me that I had made a mistake and left a "2" out. I have fixed this mistake.
    Last edited by topsquark; October 11th 2007 at 06:17 AM. Reason: It's always the details...
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