Trapezoid

Trapezoid (American English) Trapezium (British English)
Trapezoid or trapezium
Type	quadrilateral
Edges and vertices	4
Area	${\displaystyle {\tfrac {1}{2}}(a+b)h}$
Properties	convex

Look up trapezoid in Wiktionary, the free dictionary.

In geometry, a trapezoid (/ˈtræpəzɔɪd/) in North American English, or trapezium (/trəˈpiːziəm/) in British English,^[1][2] is a quadrilateral that has at least one pair of parallel sides.

The parallel sides are called the bases of the trapezoid.^[3] The other two sides are called the legs^[3] or lateral sides. (If the trapezoid is a parallelogram, then the choice of bases and legs is arbitrary.)

A trapezoid is usually considered to be a convex quadrilateral in Euclidean geometry, but there are also crossed cases. If ABCD is a convex trapezoid, then ABDC is a crossed trapezoid. The metric formulas in this article apply in convex trapezoids.