Trapezoid



(but see definition notes below) quadrilateral which has at least one pair of parallel sides

Try this Drag the orange dots on each Drag the orange dots on each vertex to reshape the figure. Notice that the sides AB and CD remain parallel.

Attributes

Base One of the parallel sides. Every trapezoid has two bases. See Base definitions. Leg The sides AC and BD above are called the legs of the trapezoid, and are usually not parallel, although they could be (see parallelogram note below). Every trapezoid has two legs. Altitude The altitude of a trapezoid is the perpendicular distance from one base to the other. (One base may need to be extended). Median The median of a trapezoid is a line joining the midpoints of the two legs. See Trapezoid median Area The usual way to calculate the area is the average base length times altitude. See Area of a Trapezoid Perimeter The distance a round the trapezoid. The sum of its side lengths. See Perimeter of a Trapezoid

If both legs are the same length, this is called an isosceles trapezoid, and both base angles are the same.

If the legs are parallel, it now has two pairs of parallel sides, and is a parallelogram.

Coordinate Geometry

Definition notes

British USA Trapezoid A quadrilateral with no sides parallel A quadrilateral with one pair of parallel sides Trapezium A quadrilateral with one pair of parallel sides A quadrilateral with no sides parallel

Other polygon topics

General

Types of polygon

Area of various polygon types

Perimeter of various polygon types

Angles associated with polygons

Named polygons

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