# GED Math : Parallel and Perpendicular Lines

## Example Questions

### Example Question #787 : Geometry And Graphs

Given the equation ,  what is the slope of another line that is parallel to this line?

Explanation:

When lines are parallel, their slopes are equal.

Rewrite the given equation in standard form to slope-intercept form:

Subtract  from both sides.

Divide by negative seven on both sides.

The equation becomes:

### Example Question #788 : Geometry And Graphs

What is the slope of the line that is perpendicular to the line ?

Explanation:

Start by putting the given equation of a line in slope-intercept form.

The slope of the given line is .

Next, recall that the slope of perpendicular lines are negative reciprocals. To get the negative reciprocal, change the sign of the given slope and flip the numerator and denominator.

The negative reciprocal of  is .

### Example Question #789 : Geometry And Graphs

If a line is , what is the slope of the perpendicular line?

Explanation:

The equation of the line is the slope is in slope-intercept form:

The slope is three.

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

Substitute the slope into the equation.

### Example Question #790 : Geometry And Graphs

Which of the following lines is parallel to the line ?

Explanation:

Start by placing the given equation in slope-intercept form.

Recall that parallel lines must have the same slope. Thus,  is the only line that is parallel to the given one.

### Example Question #791 : Geometry And Graphs

What is the slope of a line that is perpendicular to the line ?

Explanation:

Start by rewriting the equation in slope-intercept form.

Recall that perpendicular lines have slopes that are negative reciprocals of each other. To find the negative reciprocal, flip the signs, and switch the numerator and denominator around.

The negative reciprocal of  is . Thus, the line perpendicular to the given one must be .

### Example Question #792 : Geometry And Graphs

Which of the following lines is parallel to ?

Explanation:

Which of the following lines is parallel to ?

For two lines to be parallel, they must be equidistant at all points and never cross. This will only happen if the two lines have equal slope.

Recall that slope is the number in front of the x. In this case, it is negative 4

So, the only option with slope of negative 4 is:

Don't be fooled by any of the similar looking options!

### Example Question #793 : Geometry And Graphs

Which of the following lines is perpendicular to the line ?

Explanation:

Recall that perpendicular lines have slopes that are negative reciprocals.

Start by putting  into slope-intercept form.

The slope of the given line is , which means that the line perpendicular to it must have a slope of .

is the only line that has the required slope.

### Example Question #794 : Geometry And Graphs

Which of the following lines is parallel to the line ?

Explanation:

Recall that parallel lines have the same slope. Start by putting the given equation of a line in slope-intercept form.

Since the given line has a slope of , a line parallel to it must also have the same slope. Thus,  is parallel to the given line.

### Example Question #795 : Geometry And Graphs

Two lines on the coordinate plane are perpendicular. One line has slope 0.7. The other line has slope:

Explanation:

A line perpendicular to a given line has as its slope the opposite of the reciprocal of the slope of the first line. The given line has slope

.

The opposite of the reciprocal of this can be obtained by switching numerator and denominator, then changing sign. The number is , the slope of the line in question. This is the correct choice.

### Example Question #796 : Geometry And Graphs

Line  on the coordinate plane has slope . Line  is parallel to line . Give the slope of Line .