# Ratio of Similarity

## Ratio of Similarity

The coefficient k of proportionality between the lengths of an initial geometric figure and the corresponding lengths of the image of the initial figure by a similarity.

• To determine the ratio of similarity, all that is required is two points A and B and their images, A′
and B′.
Therefore, the ratio of similarity is: k = $$\dfrac{\textrm{m}\overline{\textrm{AB}}}{\textrm{m}\overline{\textrm{A’B’}}}$$.
• Synonym for constant of proportionality.