Answer:
Two triangles are said to be congruent if they are exactly identical. We know that a triangle has three angles and three sides. So, two triangles have six angles and six sides. If we can prove the any corresponding three of them of both triangles equal under certain rules, the triangles are congruent to each other. These rules are called axioms.
The method you will use depends on the information you are given about the triangles.
--> SSS(Side-Side-Side): If you know that all three sides of a triangle are congruent to the corresponding sides of another triangle, then the two triangles are congruent.
--> SAS(Side-Angle-Side): If you know that two sides and the angle between those sides are equal to the another corresponding two sides and the angle between the two sides of another triangle, then you say that the triangles are congruent by SAS axiom.
--> ASA(Angle-Side-Angle): If you know that the two angles and the side between them are equal to the two corresponding angles and the side between those angles of another triangle are equal, you may say that the triangles are congruent by ASA axiom.
--> AAS(Angle-Angle-Side): This method is similar to the ASA axiom, but they are not same. In AAS axiom also you need to have two corresponding angles and a side of a triangle equal, but they should be in angle-angle-side order.
--> RHS(Right-Hypotenuse-Side) or HL(Hypotenuse-Leg): If hypotenuses and any two sides of two right triangles are equal, the triangles are said to be congruent by RHS axiom. You can only test this rule for the right triangles.