The ray and the straight line are among the basic geometric elements. Information about them is given already at the first stage of studying the corresponding section of mathematics. What is the difference between a ray and a straight line? Information on this is set out below.

## Definition

**Ray** is a half-line, on the one hand, emanating from a specific point, on the other - not limited by anything.

**Straight line** is an infinite line on both sides passing through any two points and does not change its direction (in contrast from a curve or a broken line).

## Comparison

It can be seen from the definitions that the fundamental difference between a ray and a straight line is whether they are bounded in space. So, the ray necessarily has a beginning and continues only from one side. The straight line, in turn, has no limit from either side. In this regard, only a part of it can be drawn, which, however, also applies to the ray.

If we take an arbitrary point on a straight line, then an infinite line extending from it will be a ray. In this sense, the ray can be called part of a straight line. It is also true that the chosen point will serve as a starting point for two oppositely directed rays at once.

Comparing a ray and a straight line, one should say about the ways of their designation. Each of the geometric objects can be called a Latin lowercase letter: ray a (c, d, t) or straight b (a, h, c). Also, in both cases, the designation is used in two capital letters: the NK beam or the straight OD.

However, there are differences in the last paragraph. The letters in the name of the line, marking the points through which it is drawn, can be interchanged when reading and writing. Meanwhile, relative to the ray, its beginning is strictly indicated first, and then a point located at a certain distance from the original.

In addition, the beam has its own designation. In this case, after the capital character that names the starting point, the line on which the ray is located is indicated with a lowercase letter. Thus, the notation Bo is interpreted as follows: the ray with the origin at the point B belongs to the straight line o.

What is the difference between a ray and a straight line, apart from what has been said? In that the rays can form an angle. To do this, they must start from one point. Do not form right angles.

## Table

Beam | Direct |

Has a beginning, is infinite on one side only | Absolutely infinite |

Denoted by: single lowercase characters, two uppercase letters, uppercase and lowercase letters (indicating the starting point ray and straight line, respectively) | Designated by: single lowercase characters, two capital letters |

The starting point always comes first in the name | The order of letters in the name is not important |

Can be an element of the angle | Does not participate in the formation of angles |