Parallel lines are a fixed distance apart and will never meet, no matter how long they are extended. Lines that are parallel have the same gradient. The graphs above, \(y = 2x + 1\) and \(y = 2x - 2\) ...

i) (Motivate) If a ray stands on a line, then the sum of the two adjacent angles so formed is 180 degrees and the converse. ii) (Prove) If two lines intersect, the vertically opposite angles are equal ...