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Math Help - Proving identity #1

  1. #1
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    Proving identity #1

    cotx+tanx=2csc2x

    LS:

    cotx+tanx
    =cosx/sinx+sinx/cosx
    =1/cosxsinx


    RS:

    2csc2x
    =2(1/sin)2x


    What should I do now?
    Last edited by mr fantastic; August 12th 2009 at 04:24 PM. Reason: Changed post title
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  2. #2
    A riddle wrapped in an enigma
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    Quote Originally Posted by skeske1234 View Post

    \cot x+\tan x=2\csc 2x

    LS:

    \cot x+\tan x=

    \frac{\cos x}{\sin x}+\frac{\sin x}{\cos x}=

    {\color{red}\frac{1}{\sin x \cos x}=}


    RS:

    Try this instead: Recall that \sin 2x = 2 \sin x \cos x

    =\frac{2}{\sin 2x}

    =\frac{2}{2 \sin x \cos x}

    {\color{red}=\frac{1}{\sin x \cos x}}

    ..
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  3. #3
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    Quote Originally Posted by skeske1234 View Post
    cotx+tanx=2csc2x

    LS:

    cotx+tanx
    =cosx/sinx+sinx/cosx
    =1/cosxsinx ... multiply numerator and denominator by 2


    RS:

    2csc2x
    =2(1/sin)2x ... 2/[sin(2x)]


    What should I do now?
    .
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