https://math.libretexts.org › Bookshelves › Geometry › Euclidean_Plane_and_its_Relatives...

The subset of line \((PQ)\) between \(P\) and \(Q\) is called the segment between \(P\) and \(Q\) and denoted by \([PQ]\). Formally, the segment can be defined as the intersection of two half-lines: \([PQ] = [PQ) \cap [QP)\).

https://www.sciencedirect.com › topics › mathematics › half-line

Definition. Given a line l ∈ Λ, a point A ∈ l and a natural order ≤ l on l, then the set. ρ l, A, ≤ l = { P ∈ l: A ≤ l P }, is called a half-line or ray of l, with initial pointA. Given distinct points A, B let ≤ l be the natural order on l = AB for which A ≤ l B; then we also use the notation [ A, B for ρ ( l, A ,≤ l ). Figure 2.4.

https://en.wikipedia.org › wiki › Line_(geometry)

Given a line and any point A on it, we may consider A as decomposing this line into two parts. Each such part is called a ray and the point A is called its initial point. It is also known as half-line, a one-dimensional half-space. The point A is considered to be a member of the ray.

https://en.wikiversity.org › wiki › Points,_lines,_and_planes

A ray (or half-line) is a line that terminates at one of its points. It travels to infinity on one side of its two defining points, and terminates on the other. [1] Ray. In the picture above, points A and C define a line that terminates at point A. Therefore the ray is defined by points A and C. Like a straight line, a ray is one-dimensional.

https://math.info › Geometry › Lines_Rays_Segments

A ray is occasionally referred to as a half line. Rays begin at one point and continue indefinitely in a single direction after passing through another point (reference illustration below): Similar to the methodology described above, a single arrowhead overbar is used to denote a ray. Accordingly, the ray above may be denoted as:

https://www.alloprof.qc.ca › en › students › vl › mathematics › straight-lines-and-half-planes-m1317

In geometry, a straight line is a line formed by an infinite number of aligned points. A straight line represented in a Cartesian plane can be horizontal, vertical, or oblique. A half-plane represents a portion of a plane on one side of a straight line dividing the plane.