GMAT Math : Other Quadrilaterals

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #1 : Calculating The Length Of The Side Of A Quadrilateral

A trapezoid has bases of length one mile and 4,000 feet and height one-half mile. What is the length of its midsegment?

Possible Answers:

Correct answer:

Explanation:

The length of the midsegment of a trapezoid is the mean of the lengths of its bases; the height is irrelevant. The bases are of length 4,000 feet and 5,280 feet; their mean is 

 feet, the length of the midsegment.

Example Question #4 : Calculating The Length Of The Side Of A Quadrilateral

A given trapezoid has an area of , a longer base of length  , and a height of . What is the length of the shorter base?

Possible Answers:

Correct answer:

Explanation:

The area  of a trapezoid with a larger base , a shorter base , and a height  is defined by the equation . Restructuring to solve for the shorter base :

Plugging in our values for , , and 

 

Example Question #5 : Calculating The Length Of The Side Of A Quadrilateral

A given trapezoid has an area of , a longer base of length  , and a height of . What is the length of the shorter base?

Possible Answers:

Correct answer:

Explanation:

The area  of a trapezoid with a larger base , a shorter base , and a height  is defined by the equation . Restructuring to solve for the shorter base :

 

Plugging in our values for , and 

Example Question #6 : Calculating The Length Of The Side Of A Quadrilateral

A given trapezoid has an area of , a longer base of length  , and a height of . What is the length of the shorter base?

Possible Answers:

Correct answer:

Explanation:

The area  of a trapezoid with a larger base , a shorter base , and a height  is defined by the equation . Restructuring to solve for the shorter base :

 

Plugging in our values for , and 

Example Question #1 : Calculating An Angle In A Quadrilateral

Parallelogram

Note: Diagram is NOT drawn to scale.

Refer to the above diagram.

Any of the following facts alone would be enough to prove that  is not a parallelogram, EXCEPT:

Possible Answers:

Any one of these facts alone would prove that  is not a parallelogram.

Correct answer:

Explanation:

Opposite sides of a parallelogram are congruent; if , then , violating this condition.

Consecutive angles of a parallelogram are supplementary; if , then , violating this condition.

Opposite angles of a parallelogram are congruent; if , then , violating this condition.

Adjacent sides of a parallelogram, however, may or may not be congruent, so the condition that  would not by itself prove that the quadrilateral is not a parallelogram.

Example Question #2 : Calculating An Angle In A Quadrilateral

Which of the following can not be the measures of the four interior angles of a quadrilateral?

Possible Answers:

All four of the other choices fit the conditions.

Correct answer:

Explanation:

The four interior angles of a quadrilateral measure a total of , so we test each group of numbers to see if they have this sum.

This last group does not have the correct sum, so it is the correct choice.

Example Question #1 : Calculating An Angle In A Quadrilateral

A circle can be circumscribed about each of the following figures except:

Possible Answers:

An isosceles triangle with its base one-half as long as either leg

A rectangle twice as long as it is wide

An isosceles trapezoid with one base three times as long as the other

A right scalene triangle

A rhombus with a  angle

Correct answer:

A rhombus with a  angle

Explanation:

A circle can be circumscribed about any triangle regardless of its sidelengths or angle measures, so we can eliminate the two triangle choices. 

A circle can be circumscribed about a quadrilateral if and only if both pairs of its opposite angles are supplementary. An isosceles trapezoid has this characteristic; this can be proved by the fact that base angles are congruent, and by the Same-Side Interior Angles Statement. For a parallelogram to have this characteristic, since opposite angles are congruent also, all angles must measure ; the rectangle fits this description, but the rhombus does not.

 

Example Question #4 : Calculating An Angle In A Quadrilateral

Rhombus  has two diagonals that intersect at point 

What is   ?

Possible Answers:

Correct answer:

Explanation:

The diagonals of a rhombus always intersect at right angles, so . The measures of the interior angles of the rhombus are irrelevant.

Example Question #5 : Calculating An Angle In A Quadrilateral

Quadrilateral  is inscribed in circle  . What is  ?

Possible Answers:

Correct answer:

Explanation:

Two opposite angles of a quadrilateral inscribed inside a circle are supplementary, so 

Example Question #6 : Calculating An Angle In A Quadrilateral

Rhombus

Note: Figure NOT drawn to scale.

The above figure is of a rhombus and one of its diagonals. What is  equal to?

Possible Answers:

Not enough information is given to answer the question.

Correct answer:

Explanation:

The four sides of a rhombus are congruent, so a diagonal of the rhombus cuts it into two isosceles triangles. The two angles adjacent to the diagonal are congruent, so the third angle, the one marked, measures:

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