Euclid's Elements Book I, Proposition 8: (Side-Side-Side SSS Congruence)

If two triangles have the two sides equal to two sides respectively, and have also the base equal to the base, they will also have the angles equal which are contained by the equal straight lines.
Click the figure bellow to see the illustration.



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Euclid's Elements Book I, Proposition 8

Congruent Triangles: SAS, SSS, ASA

Congruent Triangles: SAS, SSS, ASA
Demonstrates with animation the various relationships of angles and sides to congruency in triangles.


See animation at:
www.gogeometry.com/geometry/congruent_triangle_journey_1977.htm