Which formula is used to calculate the area of a trapezoid?

To find the area of a trapezoid, the formula used is based on the average of the lengths of the two parallel sides (often referred to as the "top" and "bottom") multiplied by the height of the trapezoid. The correct formula is expressed as 0.5 times the height times the sum of the lengths of the two bases:

Area = 0.5 x height x (top + bottom)

This formula reflects that you first calculate the average of the two parallel sides by adding their lengths and then dividing by two. This average base length is then multiplied by the height, which is the perpendicular distance between the two bases. This method effectively allows the calculation of the area by framing the trapezoid as a series of rectangles truncated by the two bases.

The other options do not provide the correct calculation or concept necessary to find the area of a trapezoid. For example, simply multiplying the height by the sum of the bases (as seen in some choices) does not account for averaging the bases, leading to errors in area calculation. Understanding the significance of the height in conjunction with the average of the bases is crucial for accurate measurements of area in geometric figures like trapezoids.