what is one way that a line is the same as a ray
Line (geometry) When a geometry is described by a set of axioms, the notion of a line is usually left undefined (a so-called primitive object). The properties of lines are then determined by the axioms which refer to them. One advantage to this approach is the flexibility it gives to users of the geometry. Thus in differential geometry a line may be interpreted as a geodesic (shortest path between points), while in some projective geometries a line is a 2-dimensional vector space (all linear combinations of two independent vectors). This flexibility also extends beyond mathematics and, for example, permits physicists to think of the path of a light ray as being a line.
Yellow line (road marking) A yellow line (solid or dashed) indicates that crossing the line will place a driver in a lane where opposing traffic is coming at the driver. A double yellow line is a painted marking separating two lanes of a road. It consists of two parallel, solid yellow lines, and its presence usually indicates a no-passing restriction or no passing zone, where crossing the line is prohibited. Obvious exceptions to this no-passing restriction include emergency maneuvers or temporary traffic flow changes due to road work. Often the double yellow line has sections where one of the lines becomes dashed (in which case it is no longer a "double yellow"), indicating to the drivers traveling on the side closest to the dashed line that they may pass when it is safe. Double-yellow lines may be used to separate lanes of traffic traveling in opposite directions where passing would be dangerous, or to restrict access to lanes traveling in the same direction, such as HOV and express lanes on a highway.