# What is Congruence? | Mathematics

February 9, 2016

What is Congruence? | Mathematics

Have you been studying for the TASC Test Assessing Secondary Completion™ Mathematics subtest? Have you come across the term congruence? What does it mean?

Congruence is a geometric term that means equal in size and shape, according to Math Open Reference. Math Is Fun notes that once a shape goes through a transformation of turning, flipping, or sliding, and still has the same size, area, angles, and line lengths, the new shape and the original shape are congruent.

Image via Math Is Fun.

The symbol for congruence is written as: . To use it in an example, let’s take shape A (red) and shape B (blue):

When shape A slides to the position of shape B, we can say that AB because they have the same dimensions and shape. This is read as “A is congruent to B.”

According to Math Open Reference:

• Two line segments are congruent if they have the same length. They must lie at a different angle or position on a plane to be considered congruent. Remember, a shape must go through a transformation of turning, flipping, or sliding to be congruent.

• Two angles are congruent if they have the same measure. They can lie in different orientations or positions.

• Two circles are congruent if they are the same size. The size can be measured as the radius, diameter, or circumference. The circles can overlap.