## The Lesson

A trapezoid is a four sided shape with one pair of opposite parallel sides. ## Dictionary Definition

The Oxford English Dictionary defines a rectangle as "a quadrilateral figure having only two sides parallel."

## Parts of a Trapezoid

• The parallel sides of a trapezoid are called bases. • The other sides of a trapezoid are called legs or lateral sides. ## Properties of Trapezoids

• Only one pair of sides of a trapezoid is parallel. The other pair of sides is not parallel.

## The Perimeter of a Trapezoid

The perimeter of a trapezoid is given by the formula: In this formula, b1 and b2 are the lengths of the bases of the trapezoid and l1 and l2 are the lengths of the legs of the trapezoid.

## The Area of a Trapezoid

The area of a trapezoid is given by the formula: In this formula, b1 and b2 are the lengths of the bases of the trapezoid and h is the height of the trapezoid.

## Trapezoid, Trapezium

The shape is called a trapezoid in North America. In English speaking countries outside North America, a trapezoid is called a trapezium.

## What's in a Name?

Trapezoid and trapezium come from the Greek word "trapezion" meaning 'little table'.

## A Trapezoid is a Polygon

A trapezoid is a type of polygon. A polygon is a 2-dimensional shape with straight sides. A trapezoid is an irregular polygon. Irregular polygons have different length sides and different angles.

## A Trapezoid is a Quadrilateral

A trapezoid is a quadrilateral. A trapezoid is a four-sided polygon. Parallelograms, rectangles and squares are also quadrilaterals.