GMAT Math : Geometry

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #9 : Understanding Rays

Thingy

Name a pair of opposite rays in the above figure.

Possible Answers:

 and 

 and 

 and 

 and 

 and 

Correct answer:

 and 

Explanation:

Opposite rays are rays that have the same endpoint are on the same line, but share only the endpoint. 

Two names of opposite rays must begin with the same letter, since the first letter in the name of a ray is the endpoint. Also, the second letters must represent points collinear with each other and the endpoint, and on opposite sides of the shared endpoint. Of the five choices, only  and  together meet this criteria.

Example Question #10 : Understanding Rays

Thingy

In the above figure, which of the following gives a correct name for the union of  and ?

Possible Answers:

Correct answer:

Explanation:

 and  are noncollinear rays with the same endpoint, so their union is an angle. The shared endpoint of the rays, which here is , is the vertex of the formed angle, and is therefore the middle letter of the name of the angle; this letter is flanked by two letters representing one point on each ray, which are  and . The correct choice among those given is .

Example Question #21 : Lines

Thingy

In the above figure, give the union of  and .

Possible Answers:

Correct answer:

Explanation:

 can be seen to be completely contained in  - that is, . The union of a set and its subset is the containing set, so the correct response is .

Example Question #22 : Lines

Thingy

Give the union of  and  in the above figure.

Possible Answers:

Correct answer:

Explanation:

The diagram below shows  and  in red and green, respectively:

Thingy_x

The union of the two sets is the set of points in one or the other; this set is the entire line containing the two rays, which is .

Example Question #653 : Problem Solving Questions

Thingy

In the above figure, let  be the midpoint of . Which of the following would give another name for ?

Possible Answers:

Correct answer:

Explanation:

Below is the diagram with midpoint  of  added; also, , the ray starting at  and passing through , is in green.

Thingy x

A ray is named after, in order, its endpoint and any other point on the ray.   has  as an endpoint, and also includes the points  and , so there are two valid alternative names,  and , among the choices. The correct response is .

Example Question #23 : Lines

Thingy

In the above diagram, let  and  be the midpoints of  and , respectively, and  and  be the midpoints of  and , respectively. Which of the following is not a valid alternative name for  ?

Possible Answers:

Each of the other choices gives a valid alternative name for .

Correct answer:

Each of the other choices gives a valid alternative name for .

Explanation:

Below is the diagram with the points , and , as described, shown in green. Also, , the ray that has endpoint  and passes through , is marked in red.

Thingy_x

The ray also passes through  and , so , and —all four given names—are also valid names for the ray. 

Example Question #411 : Geometry

What is the measure of an angle complementary to a  angle?

Possible Answers:

Correct answer:

Explanation:

Complementary angles have degree measures that total , so the measure of an angle complementary to a  angle would have measure .

Example Question #2 : Calculating An Angle Of A Line

What is the measure of an angle congruent to a  angle?

Possible Answers:

Correct answer:

Explanation:

Two angles are congruent if they have the same degree measure, so an angle will be congruent to a  angle if its measure is also .

Example Question #1 : Calculating An Angle Of A Line

What is the measure of an angle supplementary to a  angle?

Possible Answers:

Correct answer:

Explanation:

Supplementary angles have degree measures that total , so the measure of an angle complementary to a  angle would have measure .

Example Question #412 : Geometry

What is the measure of an angle that is supplementary to a  angle?

Possible Answers:

Correct answer:

Explanation:

Supplementary angles have degree measures that total , so an angle supplementary to  would measure .

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