# parabola_kaiyong

Introduction to Parabola: definition and properties
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1. Try to drag P to see if the Distance[P,F] is always equal to Distance[P,directrix].
(Hint: Any point P on the parabola is equidistant from the directrix and the focus.)
2.Drag the focus F close to / far away from the directrix to see what the curve varies.
(Hint: What happens while focal length c varies?)
3.Set the directrix to be horizontal or vertical line, then determine the parabola equation in standard form by yourself.

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