Lesson 3-4 Proving lines parallel,

Postulates and Theorems Postulate 3-4 – If two lines in a plane are cut by a transversal so that corresponding angles are congruent, then the lines are parallel. Postulate 3-5 – If there is a line and a point not on the line, then there exists exactly one line through the point that is parallel to the given line Theorem If two lines in a plane are cut by a transversal so that a pair of alternate exterior angles are congruent, then the lines are parallel.

Theorem If two lines in a plane are cut by a transversal so that a pair of consecutive interior angles are supplementary, then the lines are parallel Theorem If two lines in a plane are cut by a transversal so that a pair of alternate interior angles are congruent, then the lines are parallel Theorem 3-8 – In a plane, if two lines are perpendicular to the same line, then they are parallel.

Notes Find the value of x and V S B T U l p (3x – 4)° (12x – 11)°

Notes Find the value of x and V S B T U l p (9x – 11)° (8x +4)°