Section 3.4 – Proving That Lines are Parallel

Converse of the Corresponding Angles Postulate

If two lines are cut by a transversal in such a way that corresponding angles are congruent, then the 2 lines are parallel

Converse of the Same-side Interior Angles Theorem

If two lines are cut by a transversal in such a way that same side interior angles are supplementary, then the 2 lines are parallel

Converse of the Alternate Interior Angles Theorem

If two lines are cut by a transversal in such a way that alternate interior angles are congruent, then the 2 lines are parallel

Converse of the Alternate Exterior Angles Theorem

If two lines are cut by a transversal in such a way that alternate exterior angles are congruent, then the 2 lines are parallel

THEOREM] If two coplanar lines are perpendicular to the same line, then the two lines are parallel to each other

THEOREM] If two coplanar lines are parallel to the same line, then the two lines are parallel to each other