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    Been asked to integrate, and I can't do it.
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    (Original post by Bhaal85)
    Been asked to integrate, and I can't do it.
    cos2X = 1 - 2sin^2x

    ^^^Rearrange and integrate^^^
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    (Original post by Leekey)
    cos2X = 1 - 2sin^2x

    ^^^Rearrange and integrate^^^
    I knew it was something like that, so its the integral of:

    $ (cos2x-1)/2 dx
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    (Original post by Bhaal85)
    I knew it was something like that, so its the integral of:

    $ (cos2x-1)/2 dx
    Giving:

    (Sin2x)/4 - x/2 + c
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    (Original post by Bhaal85)
    I knew it was something like that, so its the integral of:

    $ (cos2x-1)/2 dx
    Actually it's (1-cos2x)/2
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    (Original post by Leekey)
    cos2X = 1 - 2sin^2x

    ^^^Rearrange and integrate^^^
    or you could say straight away using the half angle identities: sin²x = (1/2) (1 - cos2x)
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    (Original post by mockel)
    or you could say straight away using the half angle identities: sin²x = (1/2) (1 - cos2x)
    I like to write whole damn thing from start to finish as it proves to the examiner that I actually know something even though my answers are total ****!!!
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    (Original post by shift3)
    Actually it's (1-cos2x)/2
    Well its official, I've lost it completely.
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    ∫sin²x dx



    since cos2x = 1 - 2 sin²x

    sin²x = (1/2)(1-cos2x)

    so:

    ∫sin²x dx = (1/2)∫1 - cos2x dx

    = x/2 - (1/2).sin2x + C


    Hope this helps
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    Well its official, I've lost it completely.
    Oops. Maybe i should read the whole thread before posting
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    (Original post by SUKBarracuda)
    Oops. Maybe i should read the whole thread before posting
    I got the right answer, phew.....but initially didn't know how to go about doing it, I can do parts and substitution, its just that it was something I never encountered, now I know. Cheers.
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    (Original post by SUKBarracuda)
    ∫sin²x dx



    since cos2x = 1 - 2 sin²x

    sin²x = (1/2)(1-cos2x)

    so:

    ∫sin²x dx = (1/2)∫1 - cos2x dx

    = x/2 - (1/2).sin2x + C


    Hope this helps
    Small error that i thought i'd just point out.. it's x/2 - (1/4).sin2x + C
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    yeah you're right. Just a typo though i'm sure
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    (Original post by SUKBarracuda)
    yeah you're right. Just a typo though i'm sure
    Yes, damn keyboard. :rolleyes:
 
 
 

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