Similarity (geometry).

Similarity (geometry). Similarity (geometry), the relationship between two- or three-dimensional figures having the same shape but not necessarily the same size. The angle of two similar polygons or solids are equal, but the lengths of the sides are only proportional. If one side of a figure, Q, is twice the length of the corresponding side of a similar figure, R, then all of figure Q's sides will be twice the length of the corresponding sides of figure R. A double-size enlargement of a photograph, for example, is similar to the original. In the enlargement all the distances in the original picture are increased by a factor of two. The concept of congruence is related to similarity. Congruent figures have the same shape and the same size. Any two figures that are congruent are also similar. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.