This document discusses slopes of lines. It defines slope as the ratio of rise over run between two points on a line. It describes positive, negative, zero and undefined slopes. It states the postulates that parallel lines have the same slope and perpendicular lines have slopes with a product of -1. Students are instructed to work with their group to complete problems in guided practice.

1. 3.4 Slopes of Lines
(2x + 43)
#1
HW pg. 175 #3­9
odd, 13­29
odd
September 29, 2014
BELLWORK
1. Find the value of x that make p // q.
(3x)
2. Which lines are parallel?
95
85
80
100
E
D
F
G
#3­4
3. Can you prove a // b?
4. If so, what theorem would you use?
5. Are you ready for the 3.1­3.3
Quiz
on Tuesday?
p
q
a
b
x = 43
EF // DG
yes
Alt. Interior < Converse
I hope so!

2. 3.4 Slopes of Lines
= =
HW pg. 175 #3­9
odd, 13­29
odd
September 29, 2014
3.4 Find and Use Slopes of Lines
Slope: ratio of vertical change (rise) to horizontal change (run)
between any 2 points.
Slope = rise change in y y 2 - y1
run change in x x 2 - x1
Negative Slope: falls from left to right
Positive Slope: rises from left to right
Zero Slope: horizontal line
Undefined Slope: vertical line
run (x2 - x1)
rise (y2 - y1)

3. 3.4 Slopes of Lines
HW pg. 175 #3­9
odd, 13­29
odd
September 29, 2014
Comparing Slopes: When 2 lines intersect, the steeper line has
the slope with greater absolute value.
Postulate 17: Slopes of Parallel Lines
2 lines are // iff they have the same slope.
m1 = m2
Postulate 18: Slopes of Perpendicular Lines
2 lines are iff the product of their slopes is -1.
m1 * m2 = -1

4. 3.4 Slopes of Lines
HW pg. 175 #3­9
odd, 13­29
odd
September 29, 2014
With your group, complete #3 in guided practice.

5. 3.4 Slopes of Lines
HW pg. 175 #3­9
odd, 13­29
odd
September 29, 2014

6. 3.4 Slopes of Lines
HW pg. 175 #3­9
odd, 13­29
odd
September 29, 2014

7. 3.4 Slopes of Lines
HW pg. 175 #3­9
odd, 13­29
odd
September 29, 2014
With your group,
complete problems 4 & 5 in guided practice.

8. 3.4 Slopes of Lines
HW pg. 175 #3­9
odd, 13­29
odd
September 29, 2014
HW pg. 175 #3-9 odd, 13-29 odd