structural:scholar_edition, stylistic:style_transfer, information:highlighting, quality:corruption
Definition of congruence in analytic geometry

In a Euclidean system, congruence is fundamental; it is the counterpart of equality for numbers. In analytic geometry, congruence may be defined intuitively thus: two mappings of figures onto one Cartesian coordinate system are congruent if and only if, for any two points in the first mapping, the Euclidean distance between them is equal to the Euclidean distance between the corresponding points in the second mapping.

A more formal definition states that two subsets A and B of Euclidean space R are called congruent if there exists an isometry f : R → R (an element of the Euclidean group E (n)) with f (A) = B. Congruence is an equivalence relation.