RS Aggarwal Solutions for Class 6 Chapter 12 “Parallel-lines”, Parallel lines are lines that are always the same distance apart. Because they are still the same distance from one another, parallel lines will never intersect. If the slope variable is the same, the lines are parallel. Two lines in a plane which do not meet even after extending indefinitely in either direction, are known as parallel lines. Examples of parallel lines are opposite edges of a blackboard, the opposite edges of a ruler, railway lines, etc. Topics elaborated upon in this chapter are the distance between two parallel lines, why railway lines are made parallel, parallel segments and parallel rays and how to test whether given lines are parallel.