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Trig identity question, help!- working backwards from answer watch

    • Thread Starter

    I am self teaching maths to get up to a reasonable level to start a 2nd level OU course and am now stuck on a question - can't even work backwards from the answer

    Please see the attached, I have no idea how the answer has been arrived at and would like the intermediate steps - help please - many thanks xxx

    PS this is from the C2 edexcel book if that helps?

    Name:  trig identity problem.jpg
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    • Community Assistant

    Community Assistant
    You should know that a^2 + 2ab + b^2 = (a+b)^2
    • Thread Starter

    (Original post by Mr M)
    You should know that a^2 + 2ab + b^2 = (a+b)^2

    D'oh - got it - thanks so much !!!- I have been trying to solve this the past couple of hours - a bit of lateral thinking was required then -
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