All GMAT Math Resources
Example Questions
Example Question #2 : Calculating Whether Lines Are Perpendicular
A given line has a slope of . What is the slope of any line perpendicular to ?
Not enough information provided
In order for a line to be perpendicular to another line defined by the equation , the slope of line must be a negative reciprocal of the slope of line . Since line 's slope is in the slope-intercept equation above, line 's slope would therefore be .
Given that we have a line with a slope , we can therefore conclude that any perpendicular line would have a slope .
Example Question #3 : Calculating Whether Lines Are Perpendicular
Which of the following lines are perpendicular to ?
Two answers are perpendicular to the given line.
Two answers are perpendicular to the given line.
In order for a line to be perpendicular to another line defined by the equation , the slope of line must be a negative reciprocal of the slope of line . Since line 's slope is in the slope-intercept equation above, line 's slope would therefore be .
Since in this instance the slope , . Two of the above answers have this as their slope, so therefore that is the answer to our question.
Example Question #4 : Calculating Whether Lines Are Perpendicular
Do the functions and intersect at a ninety-degree angle, and how can you tell?
It is impossible to determine from the information provided.
Yes, because and have the same y-intercept.
No, because and never intersect.
Yes, because the slope of is the reciprocal of the slope of and it has the opposite sign.
No, because and have different slopes.
Yes, because the slope of is the reciprocal of the slope of and it has the opposite sign.
If two lines intersect at a ninety-degree angle, they are said to be perpendicular. Two lines are perpendicular if their slopes are opposite reciprocals. In this case:
The two lines' slopes are reciprocals with opposing signs, so the answer is yes. Of our two yes answers, only one has the right explanation. Eliminate the option dealing with -intercepts.
Example Question #5 : Calculating Whether Lines Are Perpendicular
Find the slope of a line that is perpendicular to the line running through the points and .
Not enough information provided.
To find the slope of the line running through and , we use the following equation:
The slope of any line perpendicular to the given line would have a slope that is the negative reciprocal of , or . Therefore,
Example Question #11 : Lines
Which of the following lines is perpendicular to ?
Not enough information provided.
Given a line defined by the equation with a slope of , any line perpendicular to would have a slope that is the negative reciprocal of , . Given our equation , we know that and that .
The only answer choice with this slope is .
Example Question #12 : Lines
Which of the following lines is perpendicular to
Two of the answers are correct.
Two of the answers are correct.
Given a line defined by the equation with a slope of , any line perpendicular to would have a slope that is the negative reciprocal of , . Given our equation , we know that and that .
There are two answer choices with this slope, and .
Example Question #13 : Lines
A given line is defined by the equation . Which of the following lines would be perpendicular to line ?
Not enough information provided
For any line with an equation and slope , a line that is perpendicular to must have a slope of , or the negative reciprocal of . Given , we know that and therefore know that .
Only one equation above has a slope of : .
Example Question #14 : Lines
What is the slope of a line that is perpendicular to
For any line with an equation and slope , a line that is perpendicular to must have a slope of , or the negative reciprocal of . Given the equation , we know that and therefore know that .
Example Question #15 : Lines
Which of the following lines is perpendicular to ?
None of the lines is perpendicular
Two lines are perpendicular
Two lines are perpendicular
For any line with an equation and slope , a line that is perpendicular to must have a slope of , or the negative reciprocal of . Given the equation , we know that and therefore know that .
Given a slope of , we know that there are two solutions provided: and .
Example Question #16 : Calculating Whether Lines Are Perpendicular
What is the slope of a line perpendicular to that of
First, we need to rearrange the equation into slope-intercept form. .
Therefore, the slope of this line equals Perpendicular lines have slope that are the opposite reciprocal, or