In Geometry, two objects are congruent if they have the same size and shape. Two triangles drawn on a piece of paper are congruent if we can cut them out with scissors, and superimpose them to fit exactly, that is, without gaps or overlaps. If the triangles fit exactly, the corresponding parts are the parts that coincide. Consequently, corresponding parts of congruent triangles are congruent. Therefore, if two triangles are congruent, then their corresponding angles are congruent and their corresponding sides are also congruent.
In the figure above, if we superimpose the two triangles, will coincide with and will coincide with . Hence and are corresponding sides and and are corresponding angles. » Read more