### Online College Courses for Credit

#### FREE EDUCATIONAL RESOURCES PROVIDED by SOPHIA

##### Are you a student?
Free Professional Development
+
2 Tutorials that teach Horizontal and Vertical Lines

# Horizontal and Vertical Lines

##### Rating:
(0)
Author: Sophia Tutorial
##### Description:

In this lesson, students will learn about horizontal and vertical lines.

(more)

Sophia’s self-paced online courses are a great way to save time and money as you earn credits eligible for transfer to many different colleges and universities.*

No credit card required

29 Sophia partners guarantee credit transfer.

310 Institutions have accepted or given pre-approval for credit transfer.

* The American Council on Education's College Credit Recommendation Service (ACE Credit®) has evaluated and recommended college credit for 27 of Sophia’s online courses. Many different colleges and universities consider ACE CREDIT recommendations in determining the applicability to their course and degree programs.

Tutorial
This tutorial covers horizontal and vertical lines, through the exploration of:
1. Horizontal Lines
2. Vertical Lines
3. Graphing Horizontal and Vertical Lines

## 1. Horizontal Lines

Below is an example of a horizontal line. Because it’s horizontal, the y-coordinate is the same for all points on the line no matter what the value of x is. If you look at two points on the line, (-3, 2) and (4, 2), you can see that the y value is 2 at both points. Therefore, you can write the equation for the line as y equals 2, because the y value is always 2.

In general, all horizontal lines can be written as y = a, where a is a constant value.

Another important feature of horizontal lines is that the slope of all horizontal lines is 0, because there is no change in the y value between any two points on the line, and the numerator will always be 0 when calculating the slope between any two points on the horizontal line.

## 2. Vertical Lines

Below is an example of a vertical line. Because it’s vertical, the x-coordinate is the same for all points on the line no matter what the value of y is. If you look at two points on the line, (1, -5,) and (1, 3), you can see that the x value is 1 at both points. Therefore, you can write the equation for the line as x equals 1, because the x value is always 1.

In general, all vertical lines can be written as x = a, where a is a constant value.

Another important feature of vertical lines is that the slope of all vertical lines is undefined because there is no change in the x value between any two points on the line. You can see from the slope formula that because the x values are always the same, the denominator will always be 0 when calculating the slope between any two points on a vertical line.

## 3. Graphing Horizontal and Vertical Lines

You can also graph horizontal and vertical lines from an equation. Suppose you have y equals -3. You know that this will be a horizontal line because the y value will be -3 for all points on the line, and the graph will go through -3 on the y-axis. Therefore, to graph this equation, you find -3 on the y-axis and draw a horizontal line through the point.

Now, suppose you have x equals -4. You know that this will be a vertical line because the x value will be -4 for all points on the line, and the graph will go through -4 on the x-axis. Therefore, to graph this equation, find -4 on the x-axis and draw a vertical line through the point.

Today you learned about graphing horizontal and vertical lines. You learned that the y-coordinate for all horizontal lines is the same no matter what the value of x is, and that all horizontal lines have a slope of 0. You also learned that the x-coordinate for all vertical lines is the same no matter what the value of y is, and that all vertical lines have a slope that is undefined.

Source: This work is adapted from Sophia author Colleen Atakpu.

Formulas to Know
Slope for Horizontal Lines

Slope for Vertical Lines