Calculate the Area of a Trapezoid

A trapezoid (also known as a trapezium in British English) is a quadrilateral with two parallel sides of different lengths. This means that both of these sides can be called a base, and that the trapezoid is unique in having two bases. If want to know how to calculate the area of a trapezoid, just follow these steps.

Steps

  1. Identify the length of both bases. The bases are the two parallel sides of the trapezoid. Let's call them sides a and b. Side a is 8 cm long and side b is 13 cm long.
  2. Add the lengths of the bases. Add 8 cm and 13 cm. 8 cm + 13 cm = 21 cm.
  3. Identify the height of the trapezoid. The height of the trapezoid is perpendicular to the bases. In this example, the height of the trapezoid is 7 cm.
  4. Multiply the sum of the lengths of the bases by the height. The sum of the lengths of the bases is 21 cm and the height is 7 cm. 21 cm x 7 cm = 147 cm2.
  5. Divide the result by two. Divide 147 cm2 by 2 to get the final answer. 147 cm2/2 = 73.5 cm2. The area of the trapezoid is 73.5. You have just followed the formula for finding the area of a trapezoid, which is [(b1 + b2) x h]/2.



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