# Congruence

From EscherMath

Jump to navigationJump to searchWe would like to be able to say if two shapes are "the same" or not.

We can introduce two notions of "sameness" for triangles:

- Congruent triangles
- Two triangles are
**congruent**if they have the same side lengths and angle measures. They are the same size and shape. - Similar triangles
- Two triangles are
**similar**if they have the same angle measures. They are the same shape, but may be different sizes. We will talk more about similar shapes in another section.