The right angle congruence theorem posits that right angles are always congruent to one another. A right angle is an angle that makes a 1/4-turn of a circle and is measured at 90 degrees.
"Congruence" is synonymous with "equal" in geometry. Two right angles are always equal to each other because the relationship between the two legs of each angle does not change.
For two figures to be considered congruent, they must feature the same size and shape. This is similar to the congruence between triangles, which requires the legs and hypotenuse of each triangle to be the same length. A triangle is made up of three distinct angles, each of which must be congruent.