1. 3.6 Lines in a coordinate plane

2. Algebra 1 Review
Slope of a Line: Ratio of its vertical change to the corresponding horizontal change (“rise over run”) x y

3. Algebra 1 Review
Slope of a Line: Ratio of its vertical change to the corresponding horizontal change (“rise over run”) x y

4. Algebra 1 Review
Find the slope of the line below.

5. Algebra 1 Review
Graph the line that contains the point (2,1) and the slope of… 1) 2) 3)

6. Forms of a Line Slope-Intercept Form: m = slope b = y-intercept
Standard Form:
A,B are integers ≠ 0 and A > 0
Point-Slope Form:
m = slope (x1,y1) = point on line

7. Graphing Lines in Slope-Intercept Form
Graph the line

8. Graphing Lines in Standard Form
Graph the line 2x + 3y = 6.
Method 1: Transform to Slope-Intercept Form

9. Graphing Lines in Standard Form
Graph the line 2x + 3y = 6.
Method 2: Find intercepts

10. Using Point-Slope Form
Write an equation in point-slope form of the line through point P(-1,4) with slope 3.

11. Using Point-Slope Form
Write an equation in point-slope form of the line through the points A(-2,3) and B(1,-1).

12. Horizontal and Vertical Lines
Let’s take a look at the vertical line and horizontal line through the point (-3,1).
Horizontal Lines
Slope = 0
Equation:
Vertical Lines
Slope Undefined
Equation:

13. Horizontal and Vertical Lines
Write equations for the horizontal line and the vertical line that contain the point (2,-5).

14. Slope and Parallel Lines
Slopes of Parallel Lines:
1) If two nonvertical lines are parallel, their slopes are equal.
2) If the slopes of two distinct nonvertical lines are equal, the lines are parallel.
3) Any two vertical lines are parallel.

15. Slope and Perpendicular Lines
Slopes of Perpendicular Lines:
1) If two nonvertical lines are perpendicular, the product of their slopes is -1.
2) If the slopes of two lines have a product of -1, the lines are perpendicular.
3) Any horizontal line and vertical line are perpendicular.

16. Thinking Page
Directions: Write in paragraph form and in complete sentences. Answer the following questions. What was the teaching point of the lesson? How is it meaningful to you and relevant beyond the lesson?