HSC · Topic explainer
How do you find the area of a trapezium?
Add the two parallel side lengths, divide by two and multiply by the perpendicular distance between them. The trapezium area formula is A = ½(a + b)h. Use consistent units for a, b and h, then express the area in square units.
Worked example
A trapezium has parallel sides of 8 m and 12 m, separated by a perpendicular distance of 5 m. Their average length is (8 + 12) ÷ 2 = 10 m. Multiply by the height to get 50 m².
A sloping edge is a side length. Find the perpendicular height before substituting. In the trapezoidal rule, each trapezium estimates the area under a curve across one interval. Apply the formula to each interval and add the estimates.
Official exam practice
Find other years and marking guidance in the Mathematics Standard 2 official exam archive.