How it works
Area = ½ × (a + b) × heighta and b are the two parallel sides
- a
- one parallel side
- b
- the other parallel side
- height
- perpendicular distance between them
This is a British "trapezium" and a US "trapezoid": one pair of parallel sides. Use the perpendicular height, not a slanted edge.
Frequently asked questions
What is the area of a trapezoid with sides 8 and 5 and height 4?
26 square units, from ½ × (8 + 5) × 4.
What is the formula for a trapezoid?
Half the sum of the two parallel sides, times the height.
Which sides are a and b?
The two parallel sides. The slanted sides are not used in the area formula.
Trapezoid or trapezium?
US English calls it a trapezoid; British English calls the same shape a trapezium.