Algebra 1 : Perpendicular Lines

Study concepts, example questions & explanations for Algebra 1

varsity tutors app store varsity tutors android store

Example Questions

Example Question #21 : How To Find The Slope Of Perpendicular Lines

Find the slope of the line that is perpendicular to a line with the equation:

Possible Answers:

Correct answer:

Explanation:

Lines can be written in the slope-intercept form: 

In this equation,  is the slope and  is the y-intercept.

Lines that are perpendicular to each other have slopes that are negative reciprocals of each other. This means that you need to flip the numerator and denominator of the given slope and then change the sign.

First, find the reciprocal of .

Flip the numerator and the denominator.

Next, change the sign.

Example Question #22 : How To Find The Slope Of Perpendicular Lines

Find the slope of a line that is perpendicular to a line with the equation:

Possible Answers:

Correct answer:

Explanation:

Lines can be written in the slope-intercept form: 

In this equation,  is the slope and  is the y-intercept.

Lines that are perpendicular to each other have slopes that are negative reciprocals of each other. This means that you need to flip the numerator and denominator of the given slope and then change the sign.

First, find the reciprocal of .

Next, change the sign.

Example Question #23 : How To Find The Slope Of Perpendicular Lines

Find the slope of a line that is perpendicular to a line with the equation:

Possible Answers:

Correct answer:

Explanation:

Lines can be written in the slope-intercept form: 

In this equation,  is the slope and  is the y-intercept.

Lines that are perpendicular to each other have slopes that are negative reciprocals of each other. This means that you need to flip the numerator and denominator of the given slope and then change the sign.

First, find the reciprocal of .

Next, change the sign.

Example Question #24 : How To Find The Slope Of Perpendicular Lines

Two lines intersect at the point . Which of the following lines is perpendicular to a line with the equation: 

Possible Answers:

Correct answer:

Explanation:

Lines can be written in the slope-intercept form: 

In this equation,  is the slope and  is the y-intercept.

Lines that are perpendicular to each other have slopes that are negative reciprocals of each other. This means that you need to flip the numerator and denominator of the given slope and then change the sign.

First, find the reciprocal of .

Flip the numerator and the denominator.

Next, change the sign.

Substitute this new slope into the  position of the point-slope formula:

Insert the point  into the  and  variables of the point-slope equation. Remember that points are written in the format: .

Simplify to find the equation of the line in slope-intercept form.

Distribute.

Simplify.

Add  to both sides.

Simplify

Example Question #25 : How To Find The Slope Of Perpendicular Lines

Find the slope of a line that is perpendicular to a line with the equation .

Possible Answers:

Correct answer:

Explanation:

Lines can be written in the slope-intercept form: 

In this equation,  is the slope and  is the y-intercept.

Lines that are perpendicular to each other have slopes that are negative reciprocals of each other. This means that you need to flip the numerator and denominator of the given slope and then change the sign.

The reciprocal of  is ; therefore, the reciprocal of  is .

Next, change the sign.

Example Question #26 : How To Find The Slope Of Perpendicular Lines

Find the slope of a line that is perpendicular to a line with the equation:

Possible Answers:

Correct answer:

Explanation:

Lines can be written in the slope-intercept form: 

In this equation,  is the slope and  is the y-intercept.

Lines that are perpendicular to each other have slopes that are negative reciprocals of each other. This means that you need to flip the numerator and denominator of the given slope and then change the sign.

First, find the reciprocal of .

Next, change the sign.

Example Question #27 : How To Find The Slope Of Perpendicular Lines

Find the slope of a line that is perpendicular to a line with the equation:

Possible Answers:

Correct answer:

Explanation:

Lines can be written in the slope-intercept form: 

In this equation,  is the slope and  is the y-intercept.

Lines that are perpendicular to each other have slopes that are negative reciprocals of each other. This means that you need to flip the numerator and denominator of the given slope and then change the sign.

First, find the reciprocal of .

Flip the numerator and the denominator.

Next, change the sign.

Example Question #28 : How To Find The Slope Of Perpendicular Lines

A line with a y-intercept of  is perpendicular to another line with a slope of . Find the slope of the perpendicular line.  

Possible Answers:

Correct answer:

Explanation:

This problem can be easily solved for by remembering what defines a perpendicular line. A line is perpendicular to another when the product of the two lines' slope is  For instance, if a line has a slope of , the line perpendicular to it will have a slope of  because . Using this example, if the reference line has a slope of , that means the line of interest must have a slope of . The product of these two numbers is .

Example Question #29 : How To Find The Slope Of Perpendicular Lines

A line is perpendicular to . What is the slope of the perpendicular line?

Possible Answers:

Correct answer:

Explanation:

This problem can be easily solved for by remembering what defines a perpendicular line. A line is perpendicular to another when the product of the two lines' slope is  

For instance, if a line has a slope of , the line perpendicular to it will have a slope of  because .

Using this example, if the reference line has a slope of , that means the line of interest must have a slope of .

The product of these two numbers is .

Example Question #3581 : Algebra 1

Find the slope of the line that is perpendicular to

Possible Answers:

Correct answer:

Explanation:

To determine if two lines are perpendicular, we must compare the slopes.  To do that, we must write the equations in slope-intercept form

where m is the slope.  Perpendicular lines have slopes that are opposite reciprocals of each other.  In other words, different signs and switch the numerator and the denominator.  

In the original equation

we must write it in slope-intercept form.  To do that, we will divide each term by -5.

We see that the slope of this line is -5.  A line that is perpendicular to this line will have a slope that is the opposite reciprocal of -5.  So a perpendicular line will have a slope of .

Learning Tools by Varsity Tutors