Definitions and Assistants
A locus of points is a collection of points or other objects that satisfies a particular requirement.
A directrix is a fixed line that serves as a guide in creating our parabola
A focus is the point used to determine the parabola's openness and distance from the directrix.
A parabola is a collection of points (a locus) such that the moving locus point is always equidistant from the focus and the directrix.
Visit: http://mste.illinois.edu/dildine/sketches/parabolas.htm for an additional simulation
