1. Geometry/Trig Name: _________________________
PROVING Parallel Line Proofs Date: __________________________ n
REASONS:
A. If corresponding angles are congruent, then lines are parallel.
B. If alternate interior angles are congruent, then lines are parallel.
C. If alternate exterior angles are congruent, then lines are parallel.
D. If same side interior angles are supplementary, then lines are parallel.
E. If same side exterior angles are supplementary, then lines are parallel. l m 17 11 10 12 18 j 9 8 14 6 13 2 1 3 4 5 k 19 7 15 16 20
GIVEN Parallel Lines Reason
Ex. mÐ7 = mÐ8 j // k A
1. mÐ8 = mÐ1 ___________ ___________
2. mÐ9 + mÐ1 = 180° ___________ ___________
3. mÐ11 = mÐ ___________ ___________ 1 2 9 10
1. Given: c // d; Ð13
Prove: a // b 3 4 11 12 5 6 13 14 7 8 15 16
Statements
Reasons c d

2. Parallel Line Proofs – Page 5
2. Given: AB // CD; Ð6
Prove: BC // DE A D B 2 1 3 4 5 7 6 C E
Statements
Reasons
3. Given: BC // DE; Ð6
Prove: AB // CD A D B 2 1 3 4 5 7 6 C E
Statements
Reasons