Plane figure · Quadrilaterals
Trapezoid
Exactly one pair of parallel sides. Careful: American and British usage swap the names trapezoid and trapezium. (trapezium in British usage)
Dimensions
Results
area A
Formulas
Put a copy upside down beside it: the two make a parallelogram with base a + b and height h, so one trapezoid is half of that.
Checked: the A formula agrees with a Monte Carlo measurement of the shape itself, made from its geometric definition, every time the site is built.
Topology lens
Topologically a disc, like every figure here without a hole: Euler characteristic 1. Stretching turns it into a circle, a square or a star. More on the lens.