The relationship where if one geometric figure is congruent to a second geometric figure, and the second geometric figure is congruent to a third geometric figure, then the first geometric figure is also congruent to the third geometric figure is a fundamental concept. For example, if triangle ABC is congruent to triangle DEF, and triangle DEF is congruent to triangle GHI, then triangle ABC is congruent to triangle GHI. This holds true for any geometric figures, be they line segments, angles, or complex polygons.
This property ensures logical consistency within geometric proofs and constructions. Its application streamlines reasoning by allowing the direct linking of congruence between seemingly disparate figures, provided an intermediary connection exists. Historically, the establishment of this property provided a crucial building block for the development of more complex geometric theorems and proofs, allowing mathematicians to build upon established congruences with certainty.