Air direct fired line make up

Line possibility, infinite long-term, is described took an ideal zero width completely straight curve (deadline curve in mathematics including "straight curve") contains a infinite numeral. In the European several reeds geometries, exactly were possibly discovered through an any two coarse thread. The line provides the shortest connection between the spot. In two dimensions, two different lines are possible perhaps parallel, meant they never meet, or perhaps intersects in which only has. Perhaps in three or more dimensions, the line and is twists, meant they do not meet, moreover does not define the airplane. A two distinct airplanes intersections at most coarse thread. Lies in with 样线three or more spots calls collinear. This line intuition concept possible formalization by various way. If geometry axiomatically is developed (later and in the Euclid element and in the David Hilbert geometry foundation), the line then is not defined, but is describes by theirs product axiomatically. When Euclid defined a coarse thread as the "length not to have breadth", he has not used this quite gloomy definition in his most recent development. More abstract, you usually thought the genuine line took the line the prototype, with the supposition, selects on-line stands in pair of correspondence by the real number. But, you can and use the hyperreal numeral for this goal, even topology long line. In the European several reeds geometries, the ray, or the beam, is given two clearly selects A (origin) and B in the ray, is the wrap selects C on-line to contain selects A and B like this, A strictly is not between C and B. In the geometry, the ray starts, forever however less advanced in a direction.