GMAT Math : 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

The area of a trapezoid is 6,000 square inches. Its height is twice the length of its ionger base, which is three times the length of its shorter base. What is the height of the trapezoid?

Possible Answers:

Correct answer:

Explanation:

Let  be the length of the shorter base. Then  is the length of its longer base, and  is the height. Substitute  in the area formula:

The height is six times this, or  inches.

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 

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