Explanation:
CONGRUENT TRIANGLES : Two triangles are said to be congruent if they have same sides and exactly same angles.
Now, any two triangles can be congruent by any of the following 3 properties:
1) SIDE SIDE SIDE (SSS) : Here three sides of triangle 1 is equal to the three sides of the triangle 2.
2) SIDE ANGLE SIDE (SAS) : Here two sides and including angle of triangle 1 is equal to the two sides and including angle of the triangle 2.
3) ANGLE SIDE ANGLE (ASA) : Here two angles and including side of triangle 1 is equal to two angles and including side of the triangle 2.
4) ANGLE ANGLE SIDE (AAS) : Here two angle and one side of triangle 1 is equal to the two angles and one side of the triangle 2.