a line
collinear
ray
A half line? A ray?
This describes a ray.
if there are three or more points not all of which lie on the same line then they are known as non linear pointsif there are specifically three points not all of which lie on the same line then they are known as coplanar points as they will always lie on one plane
Noncollinear points are points which are not all on a common line.
Because the "best fit" line is usually required to be a straight line, but the data points are not all on one straight line. (If they were, then the best-fit line would be a real no-brainer.)
'Line Segment' is a portion of a line that includes two points and all of the collinear points between the hypothetical two points also 'Line Segment' because a line or line segment is a set of infinite points and the infinite points are collinear....
ray
A line can be tangent to a circle in which case it intersects it in one point, it can intersect it in two points, or no points at all. So the choices are 0,1 or 2.
Linear system
It is a RayA ray is part of a line which is finite in one direction, but infinite in the other. It can be defined by two points, the initial point, A, and one other, B. The ray is all the points in the line segment between A and B together with all points, C, on the line through A and B such that the points appear on the line in the order A, B, C.Source: Faber, Richard L. (1983). Foundations of Euclidean and Non-Euclidean Geometry. New York, United States: Marcel Dekker. ISBN 0-8247-1748-1.