Congruent Triangles

Congruent Triangles are triangles with three pairs of corresponding sides congruent and three pairs of corresponding angles congruent.

In other words, by translating, rotating, and/or flipping one triangle, you can get it to coincide exactly with the other triangle.

If ΔABC is congruent to ΔDEF, then we write

ΔABC ΔDEF.

In the figure below, ΔABC ΔDEF, but ΔABC is not congruent to ΔGHI.

Note also that we cannot write ΔABC ΔDFE. The corresponding vertices should come in the right order.