Mathematics · Grades 6–9
Area of a trapezoid
a and b are the parallel sides; h is the perpendicular distance between them.
The key idea
a and b are the parallel sides; h is the perpendicular distance between them.
A = (a + b)h/2
Worked examples
A trapezoid has parallel sides 13 cm and 21 cm and height 22 cm. Find its area in cm².
(13 + 21) × 22 ÷ 2 = 374
374 cm²
A trapezoid has parallel sides 7 cm and 11 cm and height 3 cm. Find its area in cm².
(7 + 11) × 3 ÷ 2 = 27
27 cm²
Try it yourself
A trapezoid has parallel sides 29 cm and 7 cm and height 29 cm. Find its area in cm².
A trapezoid has parallel sides 18 cm and 13 cm and height 4 cm. Find its area in cm².
Check your understanding
Answers and marking notes
- 522 cm²
(29 + 7) × 29 ÷ 2 = 522
- 62 cm²
(18 + 13) × 4 ÷ 2 = 62
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.