# Congruent Figures: Dynamic Illustration

- Author:
- Tim Brzezinski

- Topic:
- Congruence, Translation

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.