# Algebra 1 : How to find out if lines are perpendicular

## Example Questions

### Example Question #11 : How To Find Out If Lines Are Perpendicular

Find a line perpendicular to the line with the equation:

Explanation:

Lines can be written in the slope-intercept format:

In this format,  equals the line's slope and  represents where the line intercepts the y-axis.

In the given equation:

Perpendicular lines have slopes that are negative reciprocals of each other.

First, we need to find its reciprocal.

Second, we need to rewrite it with the opposite sign.

Only one of the choices has a slope of .

### Example Question #12 : How To Find Out If Lines Are Perpendicular

Find a line perpendicular to the line with the equation:

Explanation:

Lines can be written in the slope-intercept format:

In this format,  equals the line's slope and  represents where the line intercepts the y-axis.

In the given equation:

Perpendicular lines have slopes that are negative reciprocals of each other.

First, we need to find its reciprocal.

Second, we need to rewrite it with the opposite sign.

Only one of the choices has a slope of .

### Example Question #13 : How To Find Out If Lines Are Perpendicular

Find a line perpendicular to the line with the equation:

Explanation:

Lines can be written in the slope-intercept format:

In this format,  equals the line's slope and  represents where the line intercepts the y-axis.

In the given equation:

Perpendicular lines have slopes that are negative reciprocals of each other.

First, we need to find its reciprocal.

Second, we need to rewrite it with the opposite sign.

Only one of the choices has a slope of .

### Example Question #14 : How To Find Out If Lines Are Perpendicular

Find a line perpendicular to the line with the equation:

Explanation:

Lines can be written in the slope-intercept format:

In this format,  equals the line's slope and  represents where the line intercepts the y-axis.

In the given equation:

Perpendicular lines have slopes that are negative reciprocals of each other.

First, we need to find its reciprocal.

Second, we need to rewrite it with the opposite sign.

Only one of the choices has a slope of .

### Example Question #15 : How To Find Out If Lines Are Perpendicular

Find a line perpendicular to the line with the equation:

Explanation:

Lines can be written in the slope-intercept format:

In this format,  equals the line's slope and  represents where the line intercepts the y-axis.

In the given equation:

Perpendicular lines have slopes that are negative reciprocals of each other.

First, we need to find its reciprocal.

Second, we need to rewrite it with the opposite sign.

Only one of the choices has a slope of .

### Example Question #16 : How To Find Out If Lines Are Perpendicular

Find a line perpendicular to the line with the equation:

Explanation:

Lines can be written in the slope-intercept format:

In this format,  equals the line's slope and  represents where the line intercepts the y-axis.

In the given equation:

Perpendicular lines have slopes that are negative reciprocals of each other.

First, we need to find its reciprocal.

Second, we need to rewrite it with the opposite sign.

Only one of the choices has a slope of .

### Example Question #17 : How To Find Out If Lines Are Perpendicular

Find a line perpendicular to the line with the equation:

Explanation:

Lines can be written in the slope-intercept format:

In this format,  equals the line's slope and  represents where the line intercepts the y-axis.

In the given equation:

Perpendicular lines have slopes that are negative reciprocals of each other.

First, we need to find its reciprocal.

Second, we need to rewrite it with the opposite sign.

Only one of the choices has a slope of .

### Example Question #18 : How To Find Out If Lines Are Perpendicular

Find a line perpendicular to the line with the equation:

Explanation:

Lines can be written in the slope-intercept format:

In this format,  equals the line's slope and  represents where the line intercepts the y-axis.

In the given equation:

Perpendicular lines have slopes that are negative reciprocals of each other.

First, we need to find its reciprocal.

Second, we need to rewrite it with the opposite sign.

Only one of the choices has a slope of .

### Example Question #19 : How To Find Out If Lines Are Perpendicular

Given the two lines:   and , are the lines perpendicular to each other?

Explanation:

Write the perpendicular line slope formula.  The perpendicular slope is the negative reciprocal of the original slope.

Let  be the original equation.  The slope is .  Substitute this into the equation to find the slope of any perpendicular line.

The slope of a perpendicular line must have a slope of , which is also the slope for .

### Example Question #20 : How To Find Out If Lines Are Perpendicular

Select the equation of the line that is perpendicular to  .