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Say I have two points A and B positioned on the circumference of an ellipse, and they form an angle X from the center point. Now say that point A is moved to a new point C. How can I calculate the new point for B such that the angle X remains constant? Pointers to code of some kind would be appreciated.

jamesmortensen
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Kevin
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  • This is not a programming question till you work out the geometry part. Is it homework? Tag it as such. By the way, do you know polar coordinates? – jorgeca Jun 01 '12 at 21:08
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    Hi jorgeca, This isn't homework, it's for an application I'm working on. My math is pretty rusty but I'm reading up on polar coordinates again now. – Kevin Jun 01 '12 at 21:26

1 Answers1

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Why not use the polar form of an ellipse where the angle is measured from the ellipse centre??? http://en.wikipedia.org/wiki/Ellipse#Polar_form_relative_to_center From this equation, if you know the value of the angle between A and B (say theta), and you know the value of central angle of the new point C (say phi), then your required point D can be calculated from this polar form using an angle (theta + phi)

mathematician1975
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