Lines and signs
The signs are everywhere and evidence the human presence .Two lines in the same plane will always intersect unless they are parallel. Parallel lines are lines that are always the same distance apart and they never intersect. In the real world a good example of parallel lines is a railroad.The rails on a railroad track are always the same distance apart,they run in the same direction, and they never intersect. The boards(sleepers)between the rails on a track are also parallel because they do not intersect and are the same distance apart. Notice that the sleepers and the rails touch. This is called an intersection. The place that two lines intersect at is called an intersection point.