Easy (but exact) study of caustics of conics.

We give a concise summary on the technical history of visualizing implicit locus equations in the widely used dynamic geometry system GeoGebra. We mainly focus on the “draggable locus” equation, introduced in GeoGebra 5 (2014), and the dynamic envelopes. We discuss how user interface improvements (the Locus Equation and Envelope tools in GeoGebra Discovery), backend updates (the Giac subsystem) and algebraic experiments (to automatically exclude degeneracy) lead to easy study of caustics of a circle or a parabola in the classroom. [ABSTRACT FROM AUTHOR]