Use this dynamic worksheet to derive the formula for area of a trapezoid.

Use the slider to rotate the trapezoid around BD.[br]1. What shape do the two combined trapezoids form?[br]2. Let b1 represent the length of AB and b2 represent the length of CD. What is the length of the base of the shape formed by the combined trapezoids.[br]3. Write a formula for the area of the combined shape in terms of b1, b2, and h.[br]4. Write a formula for the area of a single trapezoid in terms of b1, b2, and h.