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• Two figures are congruent if they have exactly the same size and shape.

• Precisely two plane figures are said congruent, if there is a rigid motion (which does not lead to deformation), which can lead one of the two figures to coincide with another .

• When two figures are congruent, there is a correspondence between their angles and sides such that corresponding angles are congruent and corresponding sides are congruent.

In other words, they have matching angles

and matching sides

• In geometry plane, equivalence is the propriety of two or more plane figures which have the same extension.

• The equivalence is a relationship between geometric figures that do not necessarily have the same shape, but have the same area.

• These figures are equivalent because they are equally composed

• The equivalence relation has three properties which are reflexive, symmetric and transitive.

• a figure is always equivalent to itself

• if the figure a is equivalent to b, then b is equivalent to a;

• Finally, if a is equivalent to b and b is equivalent to c, then a is equivalent to c A B C

These two postcards, which are similar, aren`t the same

This feature of polygons is called similarity

There is similarity between two or more polygons if all corresponding angles are

congruent and all corresponding sides are proportional.

Figures that have the same shape, but do not have the same size, have a relationship of similarity

A B