Calculate Trapezoid Area: Finding Area of ABCD with Bases 5 and 8

A trapezoid has two different parallel sides (bases). We add them because the formula calculates the area of an 'average rectangle' - imagine the trapezoid as a rectangle with width equal to the average of the two bases.

The bases are the parallel sides of the trapezoid. In this diagram, AB (length 5) and CD (length 8) are horizontal and parallel, so they're the bases. The height is the perpendicular distance between them.

The formula stays the same! Just identify the two parallel sides (they might be vertical or diagonal) and the perpendicular distance between them. The orientation doesn't change the calculation.

This specific formula $A = \frac{1}{2}(b_1 + b_2) \times h$ only works for trapezoids. For rectangles, use length × width. For triangles, use $\frac{1}{2} \times base \times height$.

Think of it as finding the area of a rectangle with width equal to the average of the two bases. Since average = $\frac{b_1 + b_2}{2}$, we get $\frac{b_1 + b_2}{2} \times h$, which equals $\frac{1}{2}(b_1 + b_2) \times h$.