1. DRILL
1) )

2. 5.5 Areas of Trapezoids

3. Parts of a Trapezoid

4. Areas of Triangles and Trapezoids
Starting with a single trapezoid. The height is labeled h, and the bases are labeled b1 and b2
Construct a congruent trapezoid and arrange it so that a pair of congruent legs
are adjacent. b1 b2 b1 h b2
The new, composite figure is a parallelogram.
It’s base is (b1 + b2) and it’s height is the same as the original trapezoid.
The area of the parallelogram is calculated by multiplying the base X height.
A(parallelogram) = h(b1 + b2)
The area of the trapezoid is one-half of the parallelogram’s area.

5. Areas of Triangles and Trapezoids
Theorem
5-8
Area of a
Trapezoid
If a trapezoid has an area of A square units,
bases of b1 and b2 units,
and an altitude of h units, then b1 b2 h

6. Areas of Triangles and Trapezoids
Find the area of the trapezoid:
18 in
20 in
38 in
A = 522 in2

7. Ex: