Alternate Exterior Angles Theorum Proof

Alternate Exterior Angles Proof Theorum: If two parallel lines are cut by a transversal, the alternate exterior angles are congruent.

Given:Alternate Exterior Angles a is parallel to b with transversal t

Statements/Conclusion Justification
1) a is parallel to b with transversal t 1) Given
2) angle1 is congruent to angle5 2) Parallel Lines Postulate
3) angle5 is congruent to angle7 3) Vertical Angle Theorum
4) angle1 is congruent to angle7 4) Transitive Property

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