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    Can anyone please help me out with this?

    Prove that:

    cot 2x + cosec 2x = cot x

    At first I thought it looked ok, but I seem to get stuck with cos at the end.... My brain isn't functioning today. (Maths exam on monday!!) :eek:

    Thanks

    Laura xxx
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    cot 2x = cos2x/sin2x

    cosec 2x = 1/sin 2x

    so: (cos 2x + 1)/sin2x as common denominator.


    sin2x = 2sin x cos x

    cos 2x = 2cos^2 x - 1

    so: (2cos^2 x -1)/ (2sinxcosx)

    2's cancel cos x cancels with cos^2 x to leave cosx/sinx which is cot x

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    cot 2x + cosec2x
    = cos2x/sin2x + 1/sin2x
    = (cos2x + 1)/sin2x
    = 2cos²x/2sinxcosx
    = cosx/sinx
    = cotx
    =====
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    I swear I replied to this thread a few minutes ago... :confused:

    Edit:
    I thought I was imagining things, but it turns out I actually did!
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    dvs - you did reply - I read it !!! - and now I get it.

    Thanks, by the way, and thanks to the others too.
 
 
 
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Updated: June 15, 2005
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