GMAT Math : Lines

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #11 : Lines

Which of the following lines is perpendicular to 

Possible Answers:

Not enough information provided.

Correct answer:

Explanation:

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 

Possible Answers:

Two of the answers are correct.

Correct answer:

Two of the answers are correct.

Explanation:

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 ?

Possible Answers:

Not enough information provided 

Correct answer:

Explanation:

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 

Possible Answers:

Correct answer:

Explanation:

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 ?

Possible Answers:

None of the lines is perpendicular

Two lines are perpendicular 

Correct answer:

Two lines are perpendicular 

Explanation:

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 

Possible Answers:

Correct answer:

Explanation:

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 

Example Question #1 : Understanding Rays

Lines

Refer to the above figure.  and which of the following are opposite rays?

Possible Answers:

Correct answer:

Explanation:

Opposite rays begin at the same endpoint; their directions are opposite each other. Since  has endpoint , we are looking for the ray that has endpoint  and goes in the opposite direction - this ray is  .

Example Question #2 : Understanding Rays

Lines

Refer to the above figure. Which of the following is another name for  ?

Possible Answers:

None of the other choices is correct.

Correct answer:

Explanation:

A ray can be named with two letters, the first of which must be its endpoint and the second of which can be any other point on the ray.

 has endpoint . The only other marked point on the ray is , so the correct choice is .

Example Question #1 : Understanding Rays

A ray starts at the point    and has a positive slope of  .  In which quadrants does some part of the ray lie?

Possible Answers:

Correct answer:

Explanation:

A ray starts at a single point and then continues in a straight line infinitely in some direction. The given ray starts at the point  ,  which is in quadrant  , so we immediately know this must be included in the answer. The ray has a positive slope of  ,  which means the next point is  ,  followed by  ,  ,  ,  ,  and so on. By plotting these points we can visualize that the ray starts in quadrant  ,  crosses through quadrant  ,  and then continues infinitely into quadrant  ,  without ever crossing through any part of quadrant  .  The answer, therefore, is the following three quadrants:

Example Question #2 : Understanding Rays

Thingy

In the above figure, which two rays have as their union  ?

Possible Answers:

 and  

 and  

 and  

 and 

 and  

Correct answer:

 and 

Explanation:

An angle, by definition, is the union of two rays with the same endpoint. Their common endpoint is the vertex of the angle, which is always named by the middle letter of a three-letter angle name. Therefore, we are looking for two rays with endpoint . Since the first letter of the name of a ray is always its endpoint, we are looking for two rays with  as the first letter in their names. This makes  and  the correct choice.

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