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Homework Help: Elliptical motion

  1. Feb 14, 2010 #1


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    1. The problem statement, all variables and given/known data

    Hi!, can anybody help me with this problem?

    Proof that the position vector r(t) = A cos [tex]\omega[/tex]t i + B sin ([tex]\omega[/tex]t + [tex]\alpha[/tex]) moves on an ellipse.

    I understand that the parametric equation for an ellipse is x=a cos t & y=b sin t, but I just can't find any trigonometric identity that helps me. Do you know any math trick that could help me?
  2. jcsd
  3. Feb 14, 2010 #2


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    Homework Helper

    x=a cos t, y=b sin t is only for a canonical ellipse. If you find the general parametric equation for an ellipse, you'll see that your equation fits perfectly.
  4. Feb 15, 2010 #3


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    I understood what you say, but the only thing I could see was that the ellipse is rotated, but I still don't know how to prove the statement
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