There are pairs of lines that have relationships to each other that are useful to know. Perpendicular lines are at a 90° angle to each other. Parallel lines never touch and stay the same distance away from each other.
Perpendicular lines
When a line meets another at an angle of 90°, the lines are perpendicular. Examples of perpendicular lines are the corners of a piece of paper.
Parallel lines
When two lines stay the same distance apart and never touch, they are parallel. A pair of train tracks are parallel lines, for example.
Example 1
Are these lines perpendicular or parallel to each other?
These lines touch so they cannot be parallel lines.