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

2. 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

3. 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

4. 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.

5. 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

6. Examples

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