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Parametric equation question

  1. Jun 5, 2010 #1
    1. The problem statement, all variables and given/known data
    Find the length of the path over (2 cos t - cos 2t, 2 sin t - sin 2t) 0<=t<=(pi/2)

    2. Relevant equations
    sin^(2) x = (1-cos 2x)/2

    3. The attempt at a solution
    I have worked my way thru the problem and I have arrived at 2 (sq root 2) antiderivative (sq root (1-cos t)), but I'm not sure how this coverts into the relevant equation above? Thanks in advance!
  2. jcsd
  3. Jun 5, 2010 #2
    [tex]\sqrt{1 - cos(t)} = \sqrt{\frac{2(1 - cos(t))}{2}}=\sqrt{2sin^2(\frac{t}{2})}=\sqrt{2}sin(\frac{t}{2})[/tex]
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