PARALLEL LINES AND TRANSVERSALS
CORRESPONDING ANGLES POSTULATE
• Two lines cut by a transversal are parallel if and only if the pairs of corresponding angles are congruent.
ALTERNATE INTERIOR ANGLES THEOREM
• Two lines cut by a transversal are parallel if and only if the pairs of alternate interior angles are congruent.
ALTERNATE EXTERIOR ANGLES THEOREM
• Two lines but by a transversal are parallel if and only if the pairs of alternate exterior angles are congruent.
CONSECUTIVE INTERIOR ANGLES THEOREM
• Two lines cut by a transversal are parallel if and only if the pairs of consecutive interior angles are supplementary.
CONSECUTIVE EXTERIOR ANGLES THEOREM
• Two lines cut by a transversal are parallel if and only if the pairs of consecutive exterior angles are supplementary.
EXAMPLE
• Find each numbered angle.
EXAMPLE
• Find the value of x.
EXAMPLE
• Find the value of x. The picture may not be drawn to scale.
(3x + 5)o
(7x – 15)o
TRANSITIVE PROPERTY OF PARALLEL LINES
• If two lines are parallel to the same line, then they are parallel to each other.
ASSIGNMENT
• Pg. 157 #4-8 all, 27-35 odds• Pg. 165 #3-8 all