# A Parabolic Mirror

A Parabolic Mirror

Given a point F (the focus) and a line (the directrix) that lie in a plane, the locus of points in that plane that are equidistant from F and is a parabola.

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One form of the equation of a parabola is =2px, where the focal parameter is the distance from F to .

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p

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This Demonstration illustrates the reflection property of parabolas. Imagine that the parabola is a mirror and that there is a light source at the focus. Then all the reflected rays are parallel to the axis of symmetry of the parabola.