1. Axisymmetric

If a graph is folded along a straight line, then the graphs on both sides of the straight line can completely overlap each other. This graph is called an axisymmetric graph. Symmetry axis: The straight line where the crease lies is called symmetry axis.

2. Angle dividing line

Draw a ray from the vertex of an angle and divide it into two equal angles. This ray is called the bisector of an angle. The intersection of bisectors of three angles of a triangle is called the heart.

equal division

Average score (d ng-fēn). Another "equal division" is to divide an object or quantity into several equal parts. Using this method to solve the problem of polygon area often makes people feel "promising"

4. congruent triangles

Congruent triangles refers to two congruent triangles whose three sides and three angles correspond to each other. Congruent triangles is a kind of congruence in geometry. According to congruence transformation, two congruent triangles can be translated, rotated, axisymmetrical or overlapped. Two triangles are congruent triangles when their corresponding sides and angles are completely opposite. Usually, when verifying two congruent triangles, three equal parts are used to verify, and finally the result can be obtained.