(1) "Corner" is abbreviated as "SAS", and the angle between two sides and them corresponds to the congruence of two triangles ("Corner" or "SAS").

(2) "Angle" is abbreviated as "ASA", and two angles and their sides correspond to two equal triangles ("Angle" or "ASA") respectively.

(3) The abbreviation of "side" is "SSS", and three sides correspond to the congruences of two equal triangles ("side" or "SSS").

(4) The "corner edge" is called "AAS" for short, and the opposite sides of two corners and one of them correspond to the congruence of two triangles ("corner edge" or "AAS").

2. Determination of congruence of right triangle

Judging the congruence of a general triangle can prove the congruence of a right triangle.

The hypotenuse and the right-angled side correspond to the coincidence of two right-angled triangles ("hypotenuse, right-angled side" or "HL").

Note: The triangles corresponding to two diagonal angles (SSA) and triangle (AAA) are not necessarily congruent.

Small exercise

1. Known AB=AD, ∠BAE=∠DAC. To make △ ABC△ ade, the supplementary condition is _ _ _ _ _

Core Test Center: congruent triangles's Judgment

2. After finishing the door frame, Master Wang often nails two battens obliquely on the door frame. The mathematical principle of this is _ _ _ _ _.

The core test point: the stability of triangle