Starting with a plane parallel to the cone's base (defining a circle with center O), the plane is rotated by φ degrees around one axis that contains the center of the original circle (that is, around a diameter). In the resulting ellipse, how can we calculate this "original center" O, in relation to the ellipse's parameters (center, foci etc) and the angle φ?
How to calculate the position of the (right circular) cone's vertex projection upon an ellipse?
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geometry
conic-sections
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0I've seen it as I was searching for an answer, although I cannot immediately see how it can be used. If the top sphere is held constant as the other varies, the ellipse will not contain the O point. – 2012-08-07