Year 8 Interactive Maths - Second Edition

Area of a Trapezium

Consider the area of the following trapezium.

To calculate the area of a trapezium, divide it into a rectangle and two triangles as shown below.

Now, piece together the triangular ends so that the trapezium is divided into a triangle and rectangle.  The base of the triangle is the difference between the lengths of two parallel sides.  That is, a – b.

Example 4

Find the area of the following trapezium.

Solution:

So, the area of the trapezium is 204 m².

Example 5

Find the area of the following trapezium.

Solution:

So, the area of the trapezium is 39 cm².

Remember:

• A trapezium is a quadrilateral that has only one pair of parallel sides.
• The area of the trapezium is given by the following formula where a and b are the lengths of the parallel sides and h is the perpendicular distance between the parallel sides.