Chapter 5: Quadrilaterals 5-3: Theorems Involving Parallel Lines

Theorem 5-8 If two lines are parallel: then all points on one of the lines, are equidistant from the other line. A B C D AC = BD

Theorem 5-9 If three parallel lines: cut off congruent segments on one transversal, then they cut off congruent segments on every transversal. R A S T B C

Theorem 5-10 A line: that contains the midpoint of one side of a triangle and is parallel to another side passes through the midpoint of the third side.

Theorem 5-11 The segment joining the midpoints of two sides of a ∆: is parallel to the third side is half as long as the third side called a midline (or a midsegment) B DE = (½) AC D E A C

Examples

Section 5.3 WE (p. 180-181) #1-17 (all) Homework Section 5.1 WE (p. 169-170) #31-34 Section 5.3 WE (p. 180-181) #1-17 (all)