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    FP2 Jan 07 AQA Q7 for anyone interested!
    Right, I have (cosx+isinx)n=cosnx+isinnx
    I assume n=k and it works for n=1.
    The problem is I cant make the sides equal for n=k+1
    So far I have...
    (Cosx+isinx)k+1
    =(coskx+isinkx)(cosx+isinx)
    Which is correct in the mark scheme, then you multiply out and the final answer must be cos(k+1)x+isin(k+1)x.
    My problem is when multiplying out, how do I make this work.
    Does coskxisinx+isinkxcosx cancel out somehow or equal zero somehow? So confused!
    Thank you
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    (Original post by ChappersBC)
    FP2 Jan 07 AQA Q7 for anyone interested!
    Right, I have (cosx+isinx)n=cosnx+isinnx
    I assume n=k and it works for n=1.
    The problem is I cant make the sides equal for n=k+1
    So far I have...
    (Cosx+isinx)k+1
    =(coskx+isinkx)(cosx+isinx)
    Which is correct in the mark scheme, then you multiply out and the final answer must be cos(k+1)x+isin(k+1)x.
    My problem is when multiplying out, how do I make this work.
    Does coskxisinx+isinkxcosx cancel out somehow or equal zero somehow? So confused!
    Thank you
    Think of your addition formulae.
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    (Original post by Clarity Incognito)
    Think of your addition formulae.
    Oh my days! Your right, I can not believe I missed that. Thank you very much
 
 
 
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