parallel lines

Theorems


 Proving Lines Parallel

If two lines are cut by a transversal so that the alternate interior angles are congruent, then these lines are parallel

If two lines are cut by a transversal so that the corresponding angles are congruent, then these lines are parallel

If two lines are cut by a transversal so that the interior angles on the same side of the transversal are supplementary, then these lines are parallel

If two lines are cut by a transversal so that the exterior angles on the same side of the transversal are supplementary, then these lines are parallel.