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

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

The parallel sides are called the bases of the trapezoid. The other two sides are called the legs 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.