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Trig Proof

  1. Jun 5, 2008 #1

    [tex]\frac{Sec^{2}\frac{y}{2}}{2} \eqiv \frac{2}{1+x^{2}}[/tex]

    Well i know from the pythagorean identities that tan^{2}x + 1 = sec^{2}x

    [tex]\frac{tan^{2}\frac{y}{2} + 1}{2} \eqiv \frac{2}{1+x^{2}}[/tex]

    But now im stuck!

    If your interested the full qusetion is page 35, question 7 (ii) here:


    Can someone point me in the right direction

  2. jcsd
  3. Jun 5, 2008 #2


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    The actual question is:

    Given that x = tan(y/2), prove that dy/dx = 2/(1 + x²).​

    thomas49th, just differentiate both sides of x = tan(y/2). :smile:
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