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Normal unit vector

  1. Jul 17, 2010 #1
    Given the formula for an ellipse in x and y and centered on the origin, I need a formula for the x and y components of the normal unit vector at any point (x,y) on the ellipse (y>0). My calculus skills are rusty, and I haven't been able to figure this out. Thanks in advance for any help.
  2. jcsd
  3. Jul 17, 2010 #2

    Gib Z

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    Homework Helper

    Start with the equation of the ellipse. Differentiate implicitly to get the gradient of the tangent at (x,y) in terms of x and y. From that you can work out the gradient of the normal, and it's a simple application of trigonometry to separate for components.
  4. Jul 21, 2010 #3
    Thanks, Gib. That's just the nudge I needed.
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