 A Line Crosses A Pair of Parallel Lines


 If a set of 2
parallel lines, line l and line m, are crossed or cut
by another line, line n, we say "a set of parallel lines are cut by a transversal."
 Each of the parallel lines cut by the transversal has 4 angles surrounding the intersection.

 These are matched in measure and position with a counterpart at the other parallel line.

 At each of the parallel lines, there are two pairs of
vertical angle. Each angle in the pair is
congruent to the other angle in the pair.


1
4, angle 1 is congruent to angle 4.

2
3, angle 2 is congruent to angle 3.


5
8, angle 5 is congruent to angle 8.

6
7, angle 6 is congruent to angle 7.
