A plane curve formed by the intersection of a right circular cone and a plane parallel to an element of the cone or by the locus of points equidistant from a fixed line and a fixed point not on the line.
[New Latin, fromGreekparabole, comparison, application, parabola (from the relationship between the line joining the vertices of a conic and the line through its focus and parallel to its directrix), fromparaballein, to compare; see PARABLE.]
(click for a larger image)parabola
Any point on a parabola is the same distance from the directrix as it is from the focus (F). AC equals CF and BD equals DF.
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