Quadrilaterals
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GMAT Quantitative › Quadrilaterals

The above figure shows a rhombus . Give its area.
Explanation
Construct the other diagonal of the rhombus, which, along with the first one, form a pair of mutual perpendicular bisectors.

By the Pythagorean Theorem,
The rhombus can be seen as the composite of four congruent right triangles, each with legs 10 and , so the area of the rhombus is
.

Give the area of the above parallelogram if .
Explanation
Multiply height by base
to get the area.
By the 30-60-90 Theorem:
.
The area is therefore

Give the area of the above parallelogram if .
Explanation
Multiply height by base
to get the area.
By the 45-45-90 Theorem,
.
Since the product of the height and the base of a parallelogram is its area,
What is the area of a trapezoid with a height of 7, a base of 5, and another base of 13?
Explanation

Give the area of the above parallelogram if .
Explanation
Multiply height by base
to get the area.
By the 30-60-90 Theorem:
.
The area is therefore

A circle is inscribed in a square. The area of the circle is . What is the area of the square?
Explanation
Since we know the area of the circle, we can tell that: . Where
is the radius of the circle.
The length of a side of the square will be since the diameter of the circle is the same length as the side length of the square.
Finally we can calculate the area of the square which will be .
so the area will be
, which is our final answer.

Note: Figure NOT drawn to scale.
The above figure is of a rhombus and one of its diagonals. What is equal to?
Not enough information is given to answer the question.
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:
Two angles of a parallelogram measure and
. What are the possible values of
?
Explanation
Case 1: The two angles are opposite angles of the parallelogram. In this case, they are congruent, and
Case 2: The two angles are consecutive angles of the parallelogram. In this case, they are supplementary, and

In the above diagram,
.
and
. Give the area of
.
Explanation
, so
The area of the rectangle is
What is the area of the quadrilateral on the coordinate plane with vertices ?
Explanation
The quadrilateral is a parallelogram with two vertical bases, each with length . Its height is the distance between the bases, which is the difference of the
-coordinates:
. The area of the parallelogram is the product of its base and its height: