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    (Original post by James Cameron)
    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
    http://filestore.aqa.org.uk/subjects/FORMULAE.PDF
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    (Original post by James Cameron)
    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
    Use sinA + cosB = 2sin((A+B)/2)cos((A-B)/2)

    Make simultaneous equations to find A and B and then it's simple to integrate.

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    I'm absolutely baffled brother, could you guide me through the first step, if you don't mind
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    (Original post by James Cameron)
    I'm absolutely baffled brother, could you guide me through the first step, if you don't mind
    ^^^^^Look above^^^^^^
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    (Original post by powelsmartin)
    Use sinA + cosB = 2sin((A+B)/2)cos((A-B)/2)

    Make simultaneous equations to find A and B and then it's simple to integrate.

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    Sin A + COS B , are you sure?
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    (Original post by zetamcfc)
    Sin A + COS B , are you sure?
    Not really, that's from memory you should double check the formula booklet, apologies if it's wrong!

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    Some expensive wine that someone has given to me from dubaii and a box of Swiss chocolates
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    SinA +SinB = 2(Sin((A+B)/2)*Cos((A+B)/2))
    A+B=8 A-B=6
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    (Original post by zetamcfc)
    SinA +SinB = 2(Sin((A+B)/2)*Cos((A+B)/2))
    A+B=8 A-B=6
    Right, it's sinA + sinB, sorry! I seem to be failing this thread :ninja:

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    (Original post by zetamcfc)
    SinA +SinB = 2(Sin((A+B)/2)*Cos((A+B)/2))
    A+B=8 A-B=6
    Tried this for quite a while and it makes no sense to me , could you please post the first part of this solution so I can figure out the rest
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    (Original post by James Cameron)
    Tried this for quite a while and it makes no sense to me , could you please post the first part of this solution so I can figure out the rest
    So you get that A = 7x and B = 1x (by solving the simultaneous equations (A+B)/2 = 4x and (A-B)/2 = 6x)
    Then you substitute your values for A and B and the expression becomes sin1x + sin7x and you integrate that

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    (Original post by powelsmartin)
    So you get that A = 7x and B = 1x (by solving the simultaneous equations (A+B)/2 = 4x and (A-B)/2 = 6x)
    Then you substitute your values for A and B and the expression becomes sin1x + sin7x and you integrate that

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    That seems wrong, i was never taught any of that in school
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    is the answer -cosx -1/7cos7x
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    (Original post by James Cameron)
    That seems wrong, i was never taught any of that in school
    Oh yeah you got to divide the final thing by 2, sorry!

    Have you used the identity SinA + SinB = 2sin((A+B)/2)cos((A-B)/2)?

    Basically you equate the right hand side with your original expression so (A+B)/2 is 4x and (A-B)/2 is 3x and you find the values of A and B.

    Since your original expression doesn't have the 2 in front, you have to halve the final answer (which I accidentally forgot to do).

    That's the thing with A2 maths - they expect you to connect different parts of the syllabus even if you haven't done it explicitly before

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    (Original post by James Cameron)
    is the answer -cosx -1/7cos7x
    So if you take into account my previous message outlining my mistake it would be -(1/2)cosx - (1/14)cos7x + c. Never forget the + c.

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    (Original post by powelsmartin)
    Oh yeah you got to divide the final thing by 2, sorry!

    Have you used the identity SinA + SinB = 2sin((A+B)/2)cos((A-B)/2)?

    Basically you equate the right hand side with your original expression so (A+B)/2 is 4x and (A-B)/2 is 3x and you find the values of A and B.

    Since your original expression doesn't have the 2 in front, you have to halve the final answer (which I accidentally forgot to do).

    That's the thing with A2 maths - they expect you to connect different parts of the syllabus even if you haven't done it explicitly before

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    Thanks man, you've been incredibly helpful, i completely get it now
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    (Original post by James Cameron)
    Thanks man, you've been incredibly helpful, i completely get it now
    Cheers, I'm glad I could help

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