Trapezoid
A trapezoid has a pair of parallel sides. Averaging their lengths and multiplying by the perpendicular distance between them gives its area.
Give your shape a size.
Use the same unit for every dimension. Changing the unit relabels the measurements; it does not convert them.
From dimensions to an answer
Know its properties
| Sides / vertices | 4 / 4 |
| Parallel bases | a and b |
| Height | Perpendicular distance between bases |
| Angle sum | 360° |
Useful formulas
Area: A = (a + b)h / 2
Midsegment: m = (a + b) / 2
Trapezoid: common questions
Wondering about the why? Start here.
Which sides belong in the trapezoid area formula?
Use the two parallel sides a and b, together with their perpendicular separation h: A = (a + b)h/2. The nonparallel sloping sides are not the height. Parallel sides of 8 and 5 with height 4 give area 26 square units.
Explore area formulasCan I find the perimeter from the inputs here?
Not in general. Two parallel side lengths and a height determine area, but they do not uniquely determine the two remaining side lengths. To find perimeter, add all four side lengths when they are known.
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