How do we prove that triangles are congruent?

SSS - if 3 sides of a triangle are congruent to 3 sides of another triangle, then the 2 triangles are congruent .




SAS - if 2 sides of a triangle and the included angle are congruent to the 2 sides of another triangle and it's it's included angle, then the two triangles are congruent.






SAS - triangle are congruent if any two angles and their included side are equal in both triangles.