10. 1 2

11. Parallel lines Corresponding angles postulate: If 2 parallel lines are cut by a transversal, then corresponding angles are congruent….(ie.  1   2 ) 1 2 Alternate interior angles postulate: If 2 parallel lines are cut by a transversal, then alternate interior angles are congruent….(ie.  1   2 ) 1 2 1 2 Same Side interior angles postulate: If 2 parallel lines are cut by a transversal, then same side Interior angles are supplementary….(ie. m  1 + m  2=180 )

12. Proving lines parallel Corresponding angles postulate converse: If 2 lines are cut by a transversal such that corresponding angles are congruent, then the lines are parallel) 1 2 Alternate interior angles postulate converse: If 2 lines are cut by a transversal such that alternate interior angles are congruent, then the lines are parallel 1 2 1 2 Same Side interior angles postulate converse: If 2 lines are cut by a transversal such that same side Interior angles are supplementary, then the lines are parllel (* show that m  1 + m  2=180 ) *must use one of these to prove 2 lines are parallel