If two figures have exactly the same shape and size, then they are said to be congruent.

For congruence, we use the symbol ‘=’

Two plane figures are congruent, if each when superposed on the other covers it exactly.

e.g. F_{1} and F_{2} are congruent if the trace copy of F_{1} fits exactly on that F_{2}. We can write this as F_{1} = F_{2}

### Congruent Triangles

If all the sides and angles of a triangle are equal to the corresponding sides and angles of another triangle, then both the triangles are said to be congruent.

### Criteria for Congruency

### SSS Criteria for Congruency

If under a given correspondence, the three sides of one triangle are equal to the three corresponding sides of another triangle, then the triangles are congruent.

### SAS Criteria for Congruency

If under a correspondence, two sides and the angle included between them of a triangle are equal to two corresponding sides and the angle included

### ASA Criteria for Congruency

If under a correspondence, two angles and the included side of a triangle are equal to two corresponding angles and the included side of another triangle, then the triangles are congruent.

### AAS Criteria for Congruency

AAS Rule: Triangles are congruent if two pairs of corresponding angles and a pair of opposite sides are equal in both triangles.

NCERT Solutions