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    How to integrate cos^2 (4x) using double angle formula
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    (Original post by James Cameron)
    How to integrate cos^2 (4x) using double angle formula
    As you have said ... Use double angle formula

    Cos8x =
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    (Original post by TenOfThem)
    As you have said ... Use double angle formula

    Cos8x =
    i'm uncertain as to the steps required when there's a coefficient to the x
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    (Original post by TenOfThem)
    As you have said ... Use double angle formula

    Cos8x =
    Lol
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    (Original post by James Cameron)
    i'm uncertain as to the steps required when there's a coefficient to the x
    The same steps as with x on its own.
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    (Original post by zetamcfc)
    The same steps as with x on its own.
    What answer did you get
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    (Original post by James Cameron)
    How to integrate cos^2 (4x) using double angle formula
    Cos8x = 2cos^2(4x) - 1
    So cos^2(4x) = (1/2)cos8x + (1/2)
    Integrate that and you get (1/16)sin8x + (1/2)x + c

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    (Original post by James Cameron)
    What answer did you get
    Can you do the question for cos^2x by using cos2x

    If so .... This question is the same using cos8x
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    (Original post by powelsmartin)
    Cos8x = 2cos^2(4x) - 1
    So cos^2(4x) = (1/2)cos8x + (1/2)
    Integrate that and you get (1/16)sin8x + (1/2)x + c

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    Please do not post full solutions
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    (Original post by TenOfThem)
    Please do not post full solutions
    Apologies, I'm new to the forum - don't know all the rules yet!

    Posted from TSR Mobile
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    (Original post by James Cameron)
    What answer did you get
    Look at the other comments :rolleyes:
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    (Original post by powelsmartin)
    Apologies, I'm new to the forum - don't know all the rules yet!

    Posted from TSR Mobile
    No problem .... The guidelines ask us to guide and prompt ... Giving solutions only as a last resort
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    (Original post by powelsmartin)
    Cos8x = 2cos^2(4x) - 1
    So cos^2(4x) = (1/2)cos8x + (1/2)
    Integrate that and you get (1/16)sin8x + (1/2)x + c

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    Thank you so much, could you also help me find the integral of

    sin4xcos3x
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    (Original post by James Cameron)
    What answer did you get
    It is better for you to write your solution then others will check it, rather than give you the answers...
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    (Original post by zetamcfc)
    It is better for you to write your solution then others will check it, rather than give you the answers...
    OK i'll attempt to solve it now, thanks
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    (Original post by James Cameron)
    Thank you so much, could you also help me find the integral of

    sin4xcos3x
    Check your formula book first!

    You should see a very useful formula for rewriting sinAcosB in terms of other things
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    (Original post by James Cameron)
    Thank you so much, could you also help me find the integral of

    sin4xcos3x
    Do you own a formula book? The formula to use is in there (For AQA at least).
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    (Original post by zetamcfc)
    Do you own a formula book? The formula to use is in there (For AQA at least).
    WHich formula would help here?
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    (Original post by James Cameron)
    WHich formula would help here?
    AS davros said, in a previous post...
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    (Original post by zetamcfc)
    AS davros said, in a previous post...
    Well i don't have a formula book on me right now, would the formula you're talking about be sin(a+b)=sinacosb+sinbcosa
 
 
 
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