1. If the endpoint of a ray coincides with the vertex of an angle and an angle is divided into two equal angles, then the ray is the bisector of the angle.

2. In an angle, the points with equal distance to both sides of the angle are on the bisector of the angle.

The two corners have a common edge and are equal.

The bisector of the angle can get two equal angles; The distance from the point on the bisector of the angle to both sides of the angle is equal; The intersection of the three bisectors of a triangle at a point is called the center of the triangle, and the distance from the center of the triangle to the three sides of the triangle is equal.

The bisector of the angle of a triangle. The two line segments formed by the opposite sides of the bisector of the angle are proportional to the two adjacent sides of the angle.

Brief introduction of angular bisector theorem;

Angular bisector theorem (English: angular bisector theorem) is one of Euclid's basic theorems. There are two theorems about the bisector of an angle: the distance between the points on the bisector of an angle and the line segments on both sides of the angle is equal.

The bisector of the angle of a triangle and the two line segments formed by its opposite sides are proportional to the two sides of the angle. It can be proved by other knowledge in plane geometry, such as congruent triangles and sine theorem. The theorem similar to the theorem is the midline theorem, which also describes the proportional relationship between the sides of a triangle.

The earliest record of the theorem of angular bisector can be traced back to ancient Greece. Euclid of ancient Greece put forward the definition and properties of angular bisector in his book Elements of Geometry, and proved the property theorem of angular bisector, that is, the distance between a point on the angular bisector and both sides of the angle is equal.

Angular bisector theorem is one of the important mathematical tools in geometry and trigonometry, which can help solve problems such as plane vector and analytic geometry.