Geometric Definition of a Parabola: Locus Equidistant from a Point and a Line

This GeoGebra applet dynamically demonstrates the geometric definition of a parabola, which is the locus of points in a plane that are equidistant from a fixed point (the focus) and a fixed line (the directrix). Using geometric construction commands such as segments, perpendicular bisectors, orthogonal lines, and intersections, it constructs a moving point on the parabola and illustrates its dista