1. Lines, Lines, Lines!!! ~
Horizontal Lines
Vertical Lines

2. What is a Horizontal Line?
A Horizontal Line is a line that goes straight from left to right (or right to left) parallel to the x-axis of the coordinate plane.
All of the points on the line will have the same y-coordinates.

3. What’s a Vertical Line?
A Vertical Line is a line that goes straight up and down Parallel to the y-axis of the coordinate plane.
All of the points on the line will have the same x-coordinates.

4. The Possibilities for a Line’s Slope:
Positive Slope x y
m > 0
Line rises from left to right.
Negative Slope x y
m < 0
Line falls from left to right.

5. The Possibilities for a Line’s Slope:
m is undefined
Undefined Slope x y
Line is vertical.
Zero Slope x y
m = 0
Line is horizontal.
m = 2

6. Equations Horizontal and Vertical Lines
Horizontal line: y = b
Vertical line: x = a
Where b, a are Constants
x = 2
Graph: x = 2 and y = -1
x y
x y
y = -1
Vertical line
Horizontal line

7. Equations Horizontal and Vertical Lines
Let’s look at a line with a y-intercept of 4, a slope m = 0, and let (x, 4) be any point on the Horizontal line.
Y-axis
X-axis
(0,4)
(x,4)

8. Equations Horizontal and Vertical Lines
Let’s look at a line with no y-intercept b, an x-intercept 3, an undefined slope m, and let (3, y) be any point on the vertical line.
Y-axis
X-axis
(3,0)
(3, y)

9. The Equation for Horizontal Lines
Therefore…
The Equation for a Horizontal line going through the points (a, b), (7, b), (-4, b), (z, b), (3, b), (-10, b), ect is…
y = b

10. The Equation for Vertical Lines
Therefore…
The Equation for a Vertical line going through the points (a, 2), (a, a), (a, 5), (a, 7), (a, z), (a, -10), ect is…
x = a

11. Horizontal Line Practice
Find the equation for the lines passing through the following points.
1. (3, 2) and ( 8, 2)
2. (-5, 4) and ( 10, 4)
3. (1, -2) and ( 7, -2)
4. (4, 3) and ( -2, 3)

12. Vertical Line Practice
Find the equation for the lines passing through the following points.
1. (3, 5) and ( 3, -2)
2. (-5, 1) and ( -5, -1)
3. (1, -6) and ( 1, 8)
4. (4,3) and ( 4, -4)

13. Student Activity
You will now receive a worksheet. Turn the worksheet in when completed.

14. Do Not Disturb Work In Progress