1 2 1 2 PROPERTIES OF PARALLEL LINES POSTULATE POSTULATE 15 Corresponding Angles Postulate If two parallel lines are cut by a transversal, then the pairs of corresponding angles are congruent. 1 2 1 2

Do you remember??? 3 4 PROPERTIES OF PARALLEL LINES THEOREMS ABOUT PARALLEL LINES THEOREM 3.4 Alternate Interior Angles If two parallel lines are cut by a transversal, then the pairs of alternate interior angles are congruent. Do you remember??? 3 4

3 4 3 4 PROPERTIES OF PARALLEL LINES THEOREMS ABOUT PARALLEL LINES THEOREM 3.8 Alternate Interior Angles Converse THEOREM 3.4 Alternate Interior Angles If two parallel lines are cut by a transversal, then the pairs of alternate interior angles are congruent. If two parallel lines are cut by a transversal so that alternate interior angles are congruent, then the lines are parallel. 3 4 3 4

Do you remember??? 5 6 PROPERTIES OF PARALLEL LINES THEOREMS ABOUT PARALLEL LINES THEOREM 3.5 Consecutive Interior Angles If two parallel lines are cut by a transversal, then the pairs of consecutive interior angles are supplementary. Do you remember??? 5 6

Do you remember??? 5 6 m5 + m6 = 180 ° PROPERTIES OF PARALLEL LINES THEOREMS ABOUT PARALLEL LINES THEOREM 3.9 Consecutive Interior Angles Converse THEOREM 3.5 Consecutive Interior Angles If two parallel lines are cut by a transversal, then the pairs of consecutive interior angles are supplementary. If two parallel lines are cut by a transversal so that consecutive interior angles are supplementary, then the lines are parallel. If two parallel lines are cut by a transversal, then the pairs of consecutive interior angles are supplementary. If two parallel lines are cut by a transversal, then the pairs of consecutive interior angles are supplementary. If two parallel lines are cut by a transversal, so that consecutive interior angles are supplementary, then the lines are parallel. Do you remember??? 5 6 m5 + m6 = 180 °

Do you remember??? 7 8 PROPERTIES OF PARALLEL LINES THEOREMS ABOUT PARALLEL LINES THEOREM 3.6 Alternate Exterior Angles If two parallel lines are cut by a transversal, then the pairs of alternate exterior angles are congruent. Do you remember??? 7 8

7 8 7 8 PROPERTIES OF PARALLEL LINES THEOREMS ABOUT PARALLEL LINES THEOREM 3.10 Alternate Exterior Angles Converse THEOREM 3.6 Alternate Exterior Angles If two parallel lines are cut by a transversal, then the pairs of alternate exterior angles are congruent. If two parallel lines are cut by a transversal so that alternate exterior angles are congruent, then the lines are parallel. 7 8 7 8