Mensuration · JSS 1
Area of a trapezium and parallelogram
Find the area of four-sided shapes with parallel sides.
- Trapezium: Area = 12(a + b)h
- Parallelogram: Area = base × height
What the letters mean
- a, b
- the two parallel sides
- h
- the perpendicular distance between them
Worked example
A trapezium has parallel sides 6 cm and 10 cm, 4 cm apart. Find its area.
Step 1: Add the parallel sides and halve
12 × (6 + 10) = 8
Step 2: Times the height
8 × 4 = 32 cm2
Final answer: 32 cm2
See it
Play with this picture from the Area of Rectangles and Triangles lesson.
A = 5 × 3 = 15 cm²
3 rows of 5 squares = 15 squares. (Perimeter would be 16 cm.) Drag the blue corner.
Length5 cm
Height3 cm