A line segment consists of infinitely many infinitesimal line segments. If we define an infinitesimal length line segment as a gap, then there is: a line segment is composed of an infinite number of gaps.

Line segments are represented by letters A and B or lowercase letters representing their two endpoints. Sometimes these letters also represent the length of the line segment, which is recorded as line segment AB or line segment BA, line segment A .. where A and B represent the two endpoints of the line segment.

Of all the straight lines connecting two points, the line segment is the shortest. It is called the shortest line segment between two points. So the sum of two sides of a triangle is greater than the third side.

Extended data:

When looking for a straight line in an axisymmetric figure, the straight line can be divided into two parts, one of which can completely coincide with the other after being folded around the straight line 180 degrees. Such a graph constitutes a line segment diagram; Line segment is the most basic figure. A line segment has two symmetry axes, one is its median vertical line, and the other is its straight line. All meet this condition.

A line segment consists of infinite points, and the length of the line segment has nothing to do with the length of the points. Two values with different scales cannot be simply extrapolated directly. Finite and infinite cases cannot be simply extrapolated. Detailed discussion is the content of higher mathematics.

If the sum of two internal angles on the same side of a straight line is less than 180, then the two straight lines intersect at that side after extending indefinitely.

A straight line passing through the midpoint of a line segment and perpendicular to this line segment is called the median line of this line segment, also known as the "median line". The median vertical line can be regarded as a collection of points with the same distance to the two endpoints of a line segment, and the median vertical line is the symmetry axis of the line segment.

It is a very important part of junior high school geometry. The median vertical line divides a line segment into two equal line segments from the middle, and they are perpendicular to the divided line segment (at an angle of 90).