A more general kind of quadrilateral is a trapezoid, that is, a quadrilateral in which two opposite sides are parallel. Let b and be the lengths of the two parallel sides of a trapezoid DABC D as shown in Figure 3.6. Again using Theorem 63, we define the height of DABCD to be the constant distance h between the parallel sides. See if you can find the area of the trapezoid by dividing it into closed regions whose areas you already know, and then applying Axiom 6(iii). b' B C h А D b FIGURE 3.6. Trapezoid DABCD. Theorem 74. The area of a trapezoid with height h and parallel sides of lengths b and b' is given by (b +b)h Area 2