Geometry
Area of a trapezoid
Average the two parallel sides to get the median, then multiply by the perpendicular height between them.
The Formula
A = (a + b) / 2 x h
Average the two parallel sides to get the median, then multiply by the perpendicular height between them.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| a | First parallel side | linear units | One of the two bases. |
| b | Second parallel side | linear units | The other base. |
| h | Height | linear units | Perpendicular distance between the bases, not a leg. |
| A | Area | square units | Space enclosed by the trapezoid. |
What Each Symbol Means
alinear units
First parallel side
One of the two bases.
blinear units
Second parallel side
The other base.
hlinear units
Height
Perpendicular distance between the bases, not a leg.
Asquare units
Area
Space enclosed by the trapezoid.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate the area of a trapezoid page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate The Area Of A Trapezoid, filed under Math. Every number the guide produces comes from substituting into this one line.