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Thread: Cos2A.. WTH?

  1. #1

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    Cos2A.. WTH?

    Evening all,

    Just began revising my Higher maths.. the night before the prelim. Wasn't smart - i know.

    Ive come across a slight problem.. i have no idea how to do this question.

    Solve these equations, correct to 1 decimal place where necessary, for 0<=x>=360.

    5cos2x - cosx + 2 = 0

    I have absolutely no idea how i go about these type of questions. If you could help me with this one i'll hopefully be able to do others.

    Thanks,

    -Allan

  2. #2
    Frenzied Member zaza's Avatar
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    Re: Cos2A.. WTH?

    cos2x = 2cos2x -1

    -> 10cos2x -cosx-3 = 0

    -> (5cosx-3)(2cosx+1) = 0


    I'm sure you can take it from here.
    I use VB 6, VB.Net 2003 and Office 2010



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  3. #3

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    Re: Cos2A.. WTH?

    Thanks. Got 1 of the questions in my exam and i aced it

    -Allan

  4. #4
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    Re: Cos2A.. WTH?

    Oh god the higher maths. I assume your Scottish as well. thank god I am only doing int2.

  5. #5

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    Re: Cos2A.. WTH?

    I am aye. Its rubbish. Failed it (Y) :P for a second year running tbh.

    -Allan

  6. #6
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    Re: Cos2A.. WTH?

    Come on? Higher isn't that bad? There is just a lot of memory work and problem solving? What I hate is that this year is the first year that we are doing multiple choice questions.... I despise them.

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