How to Find the Area of a Trapezoid

To find the area of a trapezoid you use simple geometry skills. A trapezoid is a nifty four-sided shape with two parallel sides and two non-parallel sides. Learn the standard formula used to calculate its area.

Instructions

1. Remember that the bases of the trapezoid are the two parallel sides.

2. Draw two straight parallel lines on a piece of paper that have different lengths. Connect the two parallel lines with two straight lines to complete the four-sided figure.

3. Trace a straight line between the two parallel lines. This line is perpendicular, at right angles, to both parallel lines.

4. Recognize this line between the two bases as the height or altitude.

5. Calculate the area of a trapezoid using area = h(b1 + b2)1/2.

6. Understand that another way to look at this formula is that the two bases added together and divided by two give the median of the trapezoid.

7. Multiply this median by the height of the trapezoid and you get the area.

Tips & Warnings

• You can also find the area of a trapezoid by taking the components of the trapezoid and finding the area of each and adding them together. Trapezoids usually have two triangles and a rectangle as components.