Congruent
Anything that has the same size and shape. For example, these two triangles appear to be congruent:



Parts of shapes can be shown to be congruent using tick marks. Side AC is shown to be congruent to side DF using a mark:



If more than one set of sides is congruent, you use more marks to show which sides are congruent to which. For example, in this image, side AC is congruent to DF with one tick mark, and side AB is congruent to side DE with two marks.



You can also show that angles are congruent. In this case, angle B is congruent to angle E:



There is a symbol that is used to show congruencies. It is made up of an equal sign with a curved line above it:



So, for the above triangles you may want to write the following congruencies: