“线段、射线、直线”是几何图形中最简单的图形,也是最基本的几何概念,但却是后面继续学习几何知识的基础,同学们务必认真学习。一、从定义入手,理解三者的意义1.线段:一根拉紧的线、一根竹竿,给我们以线段的形象.就是说,直线上两点之间的部分叫做线段,这两个点叫做线段的端点.像三角形、长方形、正方体等的边长或棱长等都是线段. “Line, ray, straight line ” is the simplest figure in the geometry, but also the most basic geometric concept, but it is the basis for continuing to learn geometric knowledge, students must be careful to learn. First, from the definition to understand the meaning of the three 1. Line: a tightened line, a bamboo pole, to give us the image of the line segment, that is, the part between two points on the line is called the line, the two Point is called the end of the line segment, such as triangles, rectangles, cubes, such as the side length or edge length is the line segment.