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Homework Help: Unit Tangent For A Curve

  1. Nov 18, 2008 #1
    1. The problem statement, all variables and given/known data

    r(t) = 〈sin(t) − t cos(t), cos(t) +t sin(t), 5 t2 + 7 〉

    Find the unit tangent. T(t)=

    3. The attempt at a solution

    r'(t) = <cos(t) + tsin(t), -sin(t) + tcos(t), 10t>

    T(t) = r'(t)/ |r'(t)|

    |r(t)| = sqrt( 1 + 101t^2)

    And so on.
    Supposably according to the homework I'm wrong, completely wrong.
  2. jcsd
  3. Nov 18, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    Your derivative is wrong, completely wrong. You aren't using the product rule.
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