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Homework Help: Explain why this simplifies

  1. Sep 26, 2008 #1
    ok, i have this and know what it should simplify to, but why?

    (1-sin(x))(sin(x))-(cos(x))(0-cos(x))


    i know it simplifies to

    1-sin(x)

    but my book doesnt explain what exactly happens. could someone please shed some light and explain what exactly happens
     
  2. jcsd
  3. Sep 26, 2008 #2

    Defennder

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    I think you mistyped something. It doesn't simplify to that. Try for example x =pi/4.
     
  4. Sep 26, 2008 #3

    atyy

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    I'm parsing his message as:

    (1-sinx)(sin2x+cos2x)

    Does that make sense?

    Edit: No, I misread!
     
  5. Sep 26, 2008 #4
    thats what i kept seeing.

    i see it simplifies to one.

    the answer in the book shows the answer i previously gave over (1-sinx)^2

    then the final answer being

    1 over (1-sinx)
     
  6. Sep 26, 2008 #5
    [(1-sinx)(-sinx)-cosx(0-cosx)]/(1-sinx)^2

    then
    (1-sinx)/(1-sinx)^2

    then the final being
    (1)/(1-sinx)


    PS sorry for the double posting
     
  7. Sep 26, 2008 #6

    Defennder

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    That minus sign, which was absent in your original post, makes the whole world of difference. To simplify, just expand the numerator out and apply a trigo identity.
     
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