If two lines are intersected by a transversal
so that the corresponding angles are congruent, then the lines are parallel.
/
_____________________1/2____________________ l
3/4
______________________5/6_____________________m
7/8
/
1. / 1 = / 5 1. Given
2. / 1 = / 4 2. Vertical Angles are Equal.
3. / 5 = / 4 3. Substitution
4. Lines l and m are parallel. 4. Postulate 14: If Alternate Angles are
equal, then lines are parallel.