1. Geometry Agenda 1. ENTRANCE 2. Go over Practice
Lines in the Coordinate Plane
4. Practice
5. EXIT

2. Practice

3. 3-5 Lines in the Coordinate Plane
Chapter 3
3-5 Lines in the Coordinate Plane

4. Slope
The steepness of a line

5. Types of Slope
Positive
Negative
Zero No

6. Equations of Lines
A line is a set of points. Every line has an equation that relates the coordinates of these points.
ex: x + y = 5
(1, 4) (4, 1) (3, 2)
(2, 3) (0, 5) (5, 0)

7. Forms of a Line These are each different forms of the same equation.
x + y = 5 Standard form
y = -x Slope-Intercept form
y – 3 = -1(x -2) Point-Slope form

8. Standard Form
This equation is of the form Ax + By = C. The x and y terms are on the left side and the constant is on the right side of the equation.
x + y = 5

9. Slope-Intercept Form
This equation is of the form y = mx + b. The y term is on the left and the x term is on the right side of the equation. The value of m is the slope of the equation. The value of b is the y-intercept.
y = -x + 5

10. Point-Slope Form This equation is of the form y – y1 = m(x – x1).
The y term is on the left and the x term is on the right side of the equation. The value of m is the slope of the equation. The values x1 and y1
are the coordinates of a
point on the line.
y – 3 = -1(x – 2)
m = (2, 3)

11. Example #1
Graph.

12. Example #2
Graph.

13. Example #3
Graph.

14. Example #4
Graph.

15. Example #5
Graph.

16. Example #6
Graph.

17. Example #7
Find the equation of a line with slope -8 that contains the point (3, -6).

18. Example #8
Find the equation of a line that contains the points (4, -9) and (-1, 1).

19. Example #9
Find the equation of a line with slope -1 that contains the point (2, -4).

20. Example #10
Find the equation of a line that contains the points (5, 0) and (7, -3).

21. Example #11
Find the equation of a horizontal line through the point (5, -1).

22. Example #12
Find the equation of a vertical line through the point (-7, -5).

23. Example #13
A wheelchair ramp is being constructed at a local hospital. What is the equation of the line that represents the ramp?

24. Example #14
The equation C = $0.50d + $0.75 represents the cost (C) for purchasing d number of donuts at the local bakery.
What is the slope of the line represented by this equation?
What does the slope represent in this situation?
What is the y-intercept of the line?
What does the y-intercept represent in this situation?

25. Practice
WB 3-5 # 1, 2, 9, 11, 19, 25, 26, 33
EXIT