1. Slopes of Lines
Chapter 3-3

2. Finding Slope of a Line

3. Remember! Horizontal lines have a slope of 0.
“Read” the line from left to right.
If it is going up, the slope is positive
If it is going down, the slope is negative
Horizontal lines have a slope of 0.
Equation is y={y-intercept}
Vertical lines have “no slope” or “undefined”
Equation is x={x-intercept}

4. Find the Slope of a Line
Rise -8 2
Run

5. Let (0, 4) be (x1, y1) and (0, –3) be (x2, y2).
Find the Slope of a Line
B. Find the slope of the line.
Use the slope formula.
Let (0, 4) be (x1, y1) and (0, –3) be (x2, y2).
which is undefined.
Answer: undefined
Lesson 3-3 Example 1

6. C. Find the slope of the line.
Find the Slope of a Line
C. Find the slope of the line.
Answer:
Lesson 3-3 Example 1

7. D. Find the slope of the line.
Find the Slope of a Line
D. Find the slope of the line.
Answer: 0
Lesson 3-3 Example 1

8. A. Find the slope of the line.B C D
Lesson 3-3 CYP 1a

9. B. Find the slope of the line.A B C D
undefined 7
Lesson 3-3 CYP 1b

10. C. Find the slope of the line.–2 2 A B C D
Lesson 3-3 CYP 1c

11. D. Find the slope of the line.A B C D
undefined 3
Lesson 3-3 CYP 1d

12. Slopes of // and  lines // lines have equal slope
ex: y = 2x // y = 2x – 6
 Lines have opposite reciprocal slopes
ex: y = 5x – 3  y = x – 8

13. Determine Line Relationships
A. Determine whether and are parallel, perpendicular, or neither.
F(1, –3), G(–2, –1), H(5, 0), J(6, 3)
Find the slopes of and
Neither
Lesson 3-3 Example 3

14. Determine Line Relationships
B. Determine whether and are parallel, perpendicular, or neither.
F(4, 2), G(6, –3), H(–1, 5), J(–3, 10)
Answer:
The slopes are the same, so and are parallel.
Lesson 3-3 Example 3

15. The slopes are opposite reciprocals so they are 
Find the slope of & Determine whether they are parallel, perpendicular, or neither. A(–2, –1), B(4, 5), C(6, 1), D(9, –2)
The slopes are opposite reciprocals so they are 
Lesson 3-3 CYP 3a

16. B. Find the slope of & Determine whether they are parallel, perpendicular, or neither. A(7, –3), B(1, –2), C(4, 0), D(–3, 1)
Neither
Lesson 3-3 CYP 3a

17. Use Slope to Graph a Line
Graph the line that contains Q(5, 1) and is parallel to with M(–2, 4) and N(2, 1).
First find the slope of
Slope formula
Substitution
Simplify.
Lesson 3-3 Example 4

18. Use Slope to Graph a Line
Graph the line that contains Q(5, 1) and is parallel to with M(–2, 4) and N(2, 1).
Use Slope to Graph a Line
The slopes of two parallel lines are the same.
The slope of the line parallel to through Q(5, 1) is
Answer:
Graph the line.
Start at (5, 1).
Move down 3 units.
Then move right 4 units.
Label the point R.
Draw
Lesson 3-3 Example 4

19. Graph the line that contains R(2, –1) and is parallel to with O(1, 6) and P(–3, 1).B. C. A B C D
D. none of these
Lesson 3-3 CYP 4

20. Homework:
pg 160: # 1,2, 6 – 20, 24 – 36 even, 48