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Proving tanx/2 = cscx - cotx

  1. Feb 28, 2009 #1
    1. The problem statement, all variables and given/known data
    tanx/2 = (1-cosx)/sinx


    2. Relevant equations



    3. The attempt at a solution
    This is where i got on the right side
    i dont know where to finish...(1-cosx)/sinx
     
  2. jcsd
  3. Feb 28, 2009 #2

    Gib Z

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    Homework Helper

    Well, are you familiar with Weierstrass substitution? They are also known as t-formula:
    http://pear.math.pitt.edu/Calculus2/week3/3_2li5.html

    Another method would be to use the Double angle identities:
    [tex]\cos (2\theta) = 1- 2\sin^2 \theta[/tex] and [tex]\sin (2\theta) = 2 \sin \theta \cos \theta[/tex].

    Into those, let [itex]\theta = x/2[/itex], and put those back into what you have and simplify.
     
    Last edited by a moderator: Apr 24, 2017
  4. Mar 1, 2009 #3
    I found that a lot of people have been telling me that but i dont understand how you use that to make the sides equal is there a way you can show me step by step
     
  5. Mar 2, 2009 #4

    Gib Z

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    Homework Helper

    No really I can't ! You didn't even tell me which of the two methods I posted you want help with. Show us what you have tried to do yourself, so we can help you get over what you're stuck with.
     
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