Lines, Segments, and Rays: Definition and Difference

Lines, Segments, and Rays: Although we all identify intuitively what a line is, it is actually difficult to give a good mathematical definition. Cruelly, we can say that a line is an infinitely thin, infinitely long collection of points extending in two opposite directions. When we form lines in geometry, we use an arrow at each end to show that it extends infinitely.

Lines, Segments, and Rays

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A line can be named either utilizing two points on the line (for example, AB←→AB↔ ) or simply by a letter, usually lowercase (for example, line mm ).

A line is a figure created when two points are connected with minimum distance between them, and both the ends are extended to infinity.

A line segment has two endpoints. It includes these endpoints and all the points of the line between them. You can estimate the length of a segment, but not of a line.

A segment is named by its two endpoints, for instance, AB¯¯¯¯¯AB¯ .


A ray is a part of a line that has one endpoint and continues on infinitely in only one direction. You cannot include the length of a ray.

A ray is defined using its endpoint first, and then any other point on the ray (for example, BA−→−BA→ ).


A segment is a part of a line that has a fixed length or we can assume that both the ends of a segment are fixed. Segments, sometimes also introduced to as line segments.


What is the angle between two perpendicular lines?

The angle among the two perpendicular lines is 90 degrees.

What is a secant line?

A secant line is a line that crosses at two points with a circle.

What is a tangent line?

A tangent line is a line that meets the circle at one point.

What are the parallel lines?

Two lines are said to be parallel lines if they rest in the same plane and never meet.

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