1. EXAMPLE 1 Finding the Area of a Parallelogram SOLUTION = Abhbh Write the formula for the area of a parallelogram. = 10 Simplify. ANSWER The area of the parallelogram is 10 square meters. Find the area of the parallelogram shown. = 5 2 Substitute 5 for b and 2 for h. 

2. Find the area of the described parallelogram. 1. base = 6 in., height = 10 in. EXAMPLE 3 for Examples 2 and 3 GUIDED PRACTICE for Example 1 ANSWER 60 in. 2 2. base = 7 cm, height = 4 cm ANSWER 28 cm 2

3. 45 b 9 EXAMPLE 2 Finding an Unknown Dimension ANSWER b 45 ÷ 9 = Write a related division equation. b 5 = Simplify. The base is 5 centimeters. SOLUTION Write the formula for the area of a parallelogram. A bh = =  Substitute 45 for A and 9 for h. The area of a parallelogram is 45 square centimeters and the height is 9 centimeters. What is the base?

4. EXAMPLE 3 Estimating Area 1 b1 b = 92(3.6) = b 331.2 1 h1 h = 92(0.9) = h82.8 STEP 1 Use the scale to find the base b and the height h in kilometers. A parallelogram can be used to approximate the shape of Lake Erie. Use the map and scale to estimate the area of Lake Erie. SOLUTION 92 km = 3.6 cm b km 1 cm 92 km = 0.9 cm h km 1 cm Geography Base Height

5. EXAMPLE 3 Estimating Area STEP 2 Estimate the area of Lake Erie. =bh = 330(80) = 26,400 Write the formula for the area of a parallelogram. Round the base and the height to the nearest tens. Simplify. ANSWER The area of Lake Erie is about 26,400 square kilometers. A

6. EXAMPLE 3 for Examples 2 and 3 GUIDED PRACTICE for Examples 2 and 3 In Exercises 3 and 4, find the unknown dimension. 3. Area of parallelogram = 72 in. 2, base = 12 in., height = ? ANSWER 6 in. ANSWER 25 mm 4. Area of parallelogram = 125 mm 2, height = 5 mm, base = ?

7. EXAMPLE 3 for Examples 2 and 3 GUIDED PRACTICE for Examples 2 and 3 In Example 3, suppose the area is approximated using a different parallelogram with a base of 3.3 centimeters and a height of 0.9 centimeter. Estimate the area of Lake Erie using this parallelogram. ANSWER 300 km 80 km or 24,000 km 2 5... What If?