Trapezoid

Trapezoid

A trapezoid in American English or a trapezium in British English is a convex quadrilateral with at least one pair of parallel sides. The parallel sides are called the bases of the trapezoid and the other two sides are called the legs or the lateral sides.

Etymology

The term trapezoid was first used in English in 1570, from the Greek trapezoeides which means "table-like", from trapeza for "table" + -oeides for "shape".

Characteristics

A trapezoid is a quadrilateral with exactly one pair of parallel sides. The parallel sides are called the bases of the trapezoid, and the other two sides are called the legs. The base angles of a trapezoid are the angles on the same base of the trapezoid.

Types of Trapezoids

There are two types of trapezoids: right trapezoids and isosceles trapezoids. A right trapezoid has two adjacent right angles. An isosceles trapezoid has base angles that are equal, and therefore it has two pairs of adjacent sides that are equal in length.

Properties

The properties of the trapezoid are as follows:

• The bases are parallel by definition.
• If the legs are equal in length, then the base angles are equal. This is the definition of an isosceles trapezoid.
• The diagonals of a trapezoid bisect each other.
• The sum of the interior angles of a trapezoid is 360 degrees.

See also

• Quadrilateral
• Polygon
• Parallelogram
• Rectangle
• Rhombus
• Square

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