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Homework Help: Parametric equations for the tangent line

  1. Sep 16, 2005 #1
    Find parametric equations for the tangent line at the point (cos(-4pi/6),sin(-4pi/6),-4pi/6) on the curve x=cost, y=sint,z=t

    x(t) = _________
    y(t) = _________
    z(t) = _________

    r'(t) = <-sin(t), cos(t), 1>
    r'(0) = <0,1,1>

    my answer:
    x = cos(-4pi/6) + 0t
    y = sin(-4pi/6) +1t
    z = -4pi/6 +t

    the only part i got correct is the z, anyone know what im doing wrong?
  2. jcsd
  3. Sep 16, 2005 #2


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    Homework Helper

    You want the derivative at the tangent point, not t=0.
  4. Sep 16, 2005 #3
    yea your right, i dont know what i was thinking, thanks
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