Parallel Lines & Transversal Theorems

Alternate Exterior Angles Theorem

If two parallel lines are cut by a transversal, then each pair of alternate exterior angles are congruent. ∠1 ≅∠8 ∠5 ≅∠4

Alternate Interior Angles Theorem

If two parallel lines are cut by a transversal, then each pair of alternate interior angles are congruent. ∠2 ≅∠7 ∠6 ≅∠3

Corresponding Angles Postulate

If two parallel lines are cut by a transversal, then each pair of corresponding angles are congruent. ∠1 ≅∠3; ∠5 ≅∠7; ∠2 ≅∠4; ∠6 ≅∠8

Same Side Interior Angles Theorem

If two parallel lines are cut by a transversal, then each pair of same side interior angles are supplementary. ∠2 +∠3 = 180 ∠6 +∠7 = 180