N rays can form n(n- 1)/2 angles. N points can form n(n- 1)/2 line segments. When we start from a point and draw n rays, we can form n (n >; 1) angle. The included angle of every two rays is 180, so n rays can form n(n- 1)/2 angles.
A ray can form 0( 1- 1)/2=0 angles from a point. Two rays can form1(2-1)/2 =1angle from a point. Three rays can form 2(3- 1)/2=3 angles from a point. Four rays can form 3(4- 1)/2=6 angles from a point.
On the same straight line, when there are n endpoints, n(n- 1)/2 line segments can be formed. Count the number of individual line segments. For each of the n endpoints, it can form a line segment with (n- 1) endpoints other than itself, so * * * has n(n- 1) line segments.
The number of repeatedly calculated line segments. Line segments are calculated repeatedly between every two endpoints, so it needs to be divided by 2 to eliminate the duplication and get the final number of line segments.
Attributes of angles and line segments:
1, the angle can be divided into acute angle, right angle and obtuse angle. The degree of an angle is the length of the arc it draws from one point to another straight line. In other words, the angle is the distance between the common endpoints of two line segments. In addition, if two line segments start from a common endpoint and end at two other common endpoints, the included angle between the two line segments is the same.
2. A line segment is the shortest distance between two points, and all line segments have a midpoint, which is its center point. If two line segments are equal, their lengths are equal, and vice versa. In addition, two triangles are equivalent if their corresponding sides are equal. In other words, two triangles with equal sides are exactly the same.
3. There are some properties that can be used to solve various mathematical problems. For example, the angle can be used to calculate the area of a triangle; The length of a line segment can be used to calculate the perimeter and area of a triangle or quadrilateral. The nature of the midpoint can be used to find the center of a triangle and so on.