# Line

A **line** is the path of one point that is moving. A line is a type of geometric figure. A line has length, but no width. A line is made up of an endless number of points.

## Straight and curved lines

A line can be straight or curved. In geometry, the word *line* means a *straight line*. A straight line is the shortest distance between two points. A straight line is traced by a point moving in a direction that does not change.

A *curved line* is sometimes called a curve. The edge of a circle is not straight. It is an example of a curve.

## Line segments

A *line segment* is part of a line. Here are examples of straight line segments:

- _____ __

## Naming lines

Lines can get their names from any two points on the line. For example, if a line contains two different points, named [math]\displaystyle{ A }[/math] and [math]\displaystyle{ B }[/math], then the line can be called either [math]\displaystyle{ \overleftrightarrow{AB} }[/math], or [math]\displaystyle{ \overleftrightarrow{BA} }[/math].

Sometimes, lines are named with just one symbol. A letter such as [math]\displaystyle{ \ell }[/math] might be used.^{[1]}^{[2]}^{[3]}

## Two lines

Two lines can be:

- Parallel: Two lines are parallel if they are on the same plane and they never touch.
- Concurrent: Two lines are concurrent if they touch on one point.
- Coincident: Two lines are coincident if they are made of the same points.
- Perpendicular: Two lines are perpendicular if they make four right angles where they touch.
- Skew: In Euclidean space, two lines are skew if they are not parallel but they never touch.

## Related pages

## References

- ↑ "Compendium of Mathematical Symbols".
*Math Vault*. 2020-03-01. Retrieved 2020-08-16. - ↑ Weisstein, Eric W. "Line".
*mathworld.wolfram.com*. Retrieved 2020-08-16. - ↑ "An introduction to geometry (Geometry, Points, Lines, Planes and Angles)".
*Mathplanet*. Archived from the original on 2020-09-29. Retrieved 2020-08-16.