1. 11.3 The Area Of A Trapezoid Objective: After studying this section you will be able to find the areas of trapezoids and us the measure of a trapezoid’s median to find its area

2. The Area of a Trapezoid You saw in the last lesson that we can divide a trapezoid into simpler shapes. b2b2 b1b1 h There is a formula though to make finding the area easier.

3. TheoremThe area of a trapezoid equals one-half the product of the height and the sum of the bases. where b 1 is the length of one base, and b 2 is the length of the other base, and h is the height.

4. The Median of a Trapezoid DefinitionThe line segment joining the midpoints of the non-parallel sides of a trapezoid is called the median of the trapezoid. median

5. TheoremThe measure of the median of a trapezoid equals the average of the measures of the bases. where b 1 is the length of one base and b 2 is the length of the other base.

6. TheoremThe area of a trapezoid is the product of the median and the height. where M is the length of the median and h is the height. If we know the median then we can use a shorter formula to find the area of a trapezoid.

7. Example 1 Find the area of the trapezoid 12 cm 18 cm Example 2 7 cm Find the shorter base of the trapezoid if the area is 52, its altitude is 8, and its longer base is 10. (Hint: draw a picture)

8. Example 3 Find the median of a trapezoid with height 12 and bases 6 and 14. (Hint: draw a picture) Example 4 Find the area of the trapezoid in example 3.

9. Summary State in your own words how you can find the area of a trapezoid. Homework: worksheet