Congruent Figures: Dynamic Illustration

How it works ?

1. Recall an ISOMETRY is a transformation that preserves distance. So far, we have already explored the following isometries:

   Translation by Vector

   Rotation about a Point

   Reflection about a Line

   Reflection about a Point (same as 180-degree rotation about a point)

   For a quick refresher about isometries, see this Messing with Mona applet.

   CONGRUENT FIGURES

   Definition:

   Any two figures are said to be CONGRUENT if and only if one can be mapped perfectly onto the other using any 1 or composition of 2 (or more) ISOMETRIES.

   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.