# How to find the radius(major and minor) with the given 3 points in an ellipse?

I have 3 random points in an ellipse. Is it possible to find the radius of the ellipse?

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No. Since there are two circles containing every three points not no a line, you can take any ellipse which isn't a circle and three points on it, then there will be a circle (i. e. another ellipse) through it having different radius. –  martini May 2 '12 at 12:40
If your ellipse is axis-aligned, you need four points to uniquely determine it; if not axis-aligned, you need five points. Your problem as it stands is underdetermined. –  Guess who it is. May 2 '12 at 12:45
@martini: That's not right. Three points not on a line determine a unique circle. –  TonyK May 2 '12 at 13:02
@TonyK Upps ... you are right of course. –  martini May 2 '12 at 13:04

$$\left(\frac{x-x_{0}}{a}\right)^{2}+\left(\frac{y-y_{0}}{b}\right)^{2}=1$$