Trapezoid

$\begin{figure}\begin{center}\BoxedEPSF{Trapezoid.epsf}\end{center}\end{figure}$

A Quadrilateral with two sides Parallel. The trapezoid depicted above satisfies

$\begin{displaymath} m={\textstyle{1\over 2}}(a+b) \end{displaymath}$

and has Area

$\begin{displaymath} A={\textstyle{1\over 2}}(a+b)h=mh. \end{displaymath}$

The trapezoid is equivalent to the British definition of Trapezium.

References

Beyer, W. H. (Ed.) CRC Standard Mathematical Tables, 28th ed. Boca Raton, FL: CRC Press, p. 123, 1987.