**Parabola with a Trace**

by

Rob Walsh

A parabola is the set of points equidistant from a line, called the directrix, and a fixed point, called the focus.

Construct a parabola given a focus and directrix.

a. Use an Action Button to generate the parabola from an animation and trace of a constructed point.

b. Repeat the construction with a trace of the tangent line at the constructed point.