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Homework Help: Calc 3 reparametrize question

  1. Sep 29, 2009 #1
    1. The problem statement, all variables and given/known data

    reparametrize the curve r(t)=e^t*i+e^t*sin(t)*j+e^t*cost*k with respect to arc length measured from the point (1,0,1)in the direction of increasing t

    2. Relevant equations

    arc length= integral( r'(t) from a to b)

    3. The attempt at a solution

    i dont know how to start this question. somebody help
  2. jcsd
  3. Sep 29, 2009 #2


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    Gold Member

    Remember that the speed ds/dt is |r'(t)|. Your point (1,0,1) corresponds to t = 0 and is where you want to start measuring arc length.

    So calculate |r'(t)| = ds/dt. You should then be able to figure out s in terms of t for your substitution. And don't forget t = 0 corresponds to s = 0.
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