## GMAT Quantitative Review

**3.0**** ****Math Review**

**3.3 Geometry**

**7. Quadrilaterals**

A polygon with four sides is a *quadrilateral*. A quadrilateral in which both pairs of opposite sides are parallel is a *parallelogram*. The opposite sides of a parallelogram also have equal length.

In parallelogram *JKLM*, and ; and .

The diagonals of a parallelogram bisect each other (that is, and ).

The area of a parallelogram is equal to

.

The area of *JKLM* is equal to .

A parallelogram with right angles is a *rectangle*, and a rectangle with all sides of equal length is a *square*.

The perimeter of and the area of *WXYZ* is equal to .

The diagonals of a rectangle are equal; therefore .

A quadrilateral with two sides that are parallel, as shown above, is a *trapezoid*. The area of trapezoid *PQRS* may be calculated as follows:

.