# When is a quadrilateral also a parallelogram?

A quadrilateral is any two-dimensional geometric figure (polygon) with four straight sides and four vertices.

There are many different types of quadrilaterals. They can be concave, convex, or complex. A partial list of the most common examples includes:

square
rectangle
rhombus
kite
parallelogram
trapezoid
trapezium
two sides cross over one another)

The two diagonals of a quadrilateral always bisect one another.

When is a quadrilateral also a parallelogram?

### Comments for When is a quadrilateral also a parallelogram?

 May 07, 2014 quadrilateral and parallelogram by: Staff Answer A quadrilateral is a parallelogram when the following characteristics are true: 1. opposite sides are parallel 2. opposite sides are of equal length 3. opposite interior angles are equal (the sum of the four interior angles of every quadrilateral will always = 360°) The rectangle, square, and rhombus shown in the diagram are also parallelograms. Thanks for writing. Staff www.solving-math-problems.com

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