The method of drawing an angle needs to determine the vertex and two rays of the angle; The names of each part of an angle are vertex, starting edge and ending edge.

1, the vertex of the angle and the edge of the angle: the angle is formed by the intersection of two rays (or line segments), and the intersection of these two rays (or line segments) is called the vertex of the angle. Two rays (or line segments) drawn from the vertex of an angle are called the edges of the angle. Usually, we call these two sides the "beginning edge" and "end edge" of the angle.

2. Degree and type of angle: Angle can be measured by degree, which is called the degree of angle. In plane geometry, we usually use the counterclockwise direction to define the degree of an angle, from 0 to 360. An angle less than 90 is called an acute angle, an angle equal to 90 is called a right angle, and an angle greater than 90 but less than180 is called an obtuse angle.

The origin of mathematical angle

1, the concept of angle comes from geometry, and it is a basic concept to describe the included angle when two lines or rays intersect. The concept of angle can be traced back to ancient mathematics and astronomy. In the early days, people used angles to describe the position, direction and movement of objects.

2. In ancient mathematics, the concept of angle was originally used to measure the area and volume of land. Euclid, an ancient Greek mathematician, put forward the concept of plane geometry. He defined an angle as a figure formed by two rays or line segments drawn from a point. Under this definition, the angle can be measured in degrees, from 0 to 360 degrees.

3. In trigonometry, the concept of angle has been further expanded and perfected. Thales, an ancient Greek mathematician, put forward the concept of triangle and discovered the theorem that the sum of the three internal angles of a triangle is equal to 180. Subsequently, many mathematicians and astronomers made in-depth research on the concept of diagonal, including trigonometric function, angle system and arc system.

4. In modern mathematics, the concept of angle has penetrated into many fields, such as algebra, calculus, topology, linear algebra and so on. The concept of angle can describe the motion state of objects, the rotation and translation of rigid bodies and so on. In algebra, angles can be expressed as complex numbers or matrices, which provides a wider range for the application of angles.