Two triangles are said to be congruent if the three sides and three angles of the first triangle are equal to the corresponding sides and angles of the second triangle.
Congruency is denoted by
Conditions of congruency of triangles
SSS rule: If three sides of a triangle are equal to three sides of the other triangle, both the triangles are congruent.
SAS rule: If two sides and the included angle of one triangle are equal to the two sides and included angle of the other triangle, they are congruent.
ASA rule: If two angles and the included side of one triangle is equal to the two angles and included side of another triangle, they are congruent.
AAS rule: If two angles and the non-included side of one triangle is equal to the two angles and non-included side of another triangle, they are congruent.
RHS rule: If the length of the hypotenuse and one side of one right triangle, is equal to the length of the hypotenuse and corresponding side of the other right triangle, they are congruent.