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    Can someone help me with 9i. Not sure how to do it?
    Need some help starting off

    Thanks in advance
    http://www.ocr.org.uk/Images/144592-...hematics-3.pdf
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    (Original post by Super199)
    Can someone help me with 9i. Not sure how to do it?
    Need some help starting off

    Thanks in advance
    Your attachment hasn't worked.
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    (Original post by aoxa)
    Your attachment hasn't worked.
    Oh haha forgot to link it.
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    Wow, that's alot of work for 4 marks.

    I would start off by expanding cos(theta+45) then multiplying that by itself and then cleaning up.
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    (Original post by Super199)
    Oh haha forgot to link it.
    You're getting the LHS to simplify down to the RHS, so it's just using all the trig identities for cos^2(theta+45) and sin/cos 2theta and manipulating the expression, then simplifying
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    I think, as there are 2thetas in there I'd look at replacing the first term by using the double angle formula in terms of cos^2 theta.
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    (Original post by aoxa)
    You're getting the LHS to simplify down to the RHS, so it's just using all the trig identities for cos^2(theta+45) and sin/cos 2theta and manipulating the expression, then simplifying
    When you expand cos^2(theta+45) do you have to cos(theta+45) x cos(theta+45)?
    Seems a bit hefty
 
 
 
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