Congruent Figures: Dynamic Illustration
Recall a RIGID MOTION is a transformation that preserves distance. So far, we have already explored the following rigid motions: Translation by Vector Rotation about a Point Reflection about a Line For a quick refresher about rigid motions, see this Messing with Mona applet.
Definition: Two plane figures are CONGRUENT if and only if one can be mapped perfectly onto the other using any 1 or sequence of 2 (or more) RIGID MOTIONS (translations, reflections, and/or rotations). The applet below dynamically illustrates, by DEFINITION, what it means for any 2 figures (in this case, triangles) to be CONGRUENT. Feel free to move the BIG WHITE VERTICES of either triangle anywhere you'd like at any time.