what is the formula for the area of a trapezoid?

please include a diagram

3 answers

Try this:
http://www.analyzemath.com/Geometry_calculators/trapezoid.html
The area of a trapezoid is given by the formula where
b1, b2 are the lengths of the two bases
a is the altitude of the trapezoid

Recall that the bases are the two parallel sides of the trapezoid. The altitude (or height) of a trapezoid is the perpendicular distance between the two bases.

This is equivalent to the altitude times the average length of the bases. Since the median of a trapezoid is also the average length of the two bases, the area is also the altitude times the median length.

Area as a compound shape

-from a math website
Google is your friend:
try "area of trapezoid"

this one even has a nice applet

http://www.mathopenref.com/trapezoidarea.html