1. PRE-ALGEBRA

2. Lesson 10-1 Warm-Up

3. PRE-ALGEBRA Area: Parallelograms (10-1) area: the number of square units (squares) that the figure encloses (in other words, the number of squares that cover an area). Example: The following rectangle encloses 8 square units. If each unit is 1 cm. long on each side (1 sq. cm. or 1 cm. 2 ), then the rectangle is 8 square cm. (or 8 cm. 2 ). You can find the area of a rectangle by using the formula: area = base · height (A = bh), where the b stands for bottom and the h stands for height. In the rectangle above, the base (bottom) is 4 cm. and the height (up-down) is 2 cm., so A = 4 cm. 2 cm. = 8 sq. cm. Rule: When finding area, the dimensions (sides) of the figure must be in the same units. What is “area”? How do you find the area of a rectangle?

4. PRE-ALGEBRA Area: Parallelograms (10-1) Example: Find the area of the banner in the picture. Step 1: Convert (change) the inches to feet or feet to inches so the dimensions will all be the same. 24 in. = = = 2 ft. Step 2: Find the area. A = bh Use the formula for area of a rectangle. A = 2 4 Substitute A = 8 square ft. The area of the banner is 8 square feet (8 ft. 2 ). Since a rectangle is a parallelogram (a four-sided figure whose opposite sides are parallel), the area of a parallelogram is the same as rectangle (A = bh). However, the height in a parallelogram is the length of an altitude. The altitude is the distance perpendicular distance from the base straight to the opposite side (top). 24 in. 1 1 ft. 12 in. 24 ft. 12 1 1 2 1 How do you find the area of a parallelogram?

5. PRE-ALGEBRA Area: Parallelograms (10-1) Example: Find the area of each parallelogram. The area of each parallelogram is 28 sq. in. (28 in. 2).

6. PRE-ALGEBRA Find the area of the rectangle. Step 1:Convert units. = 1.5m Multiply. Area: Parallelograms LESSON 10-1 Additional Examples 150 cm = 150 cm Change 150 centimeters. 1m 100cm

7. PRE-ALGEBRA Step 2:Find the area. A = bhUse the formula for area of a rectangle. = (4)(1.5)Substitute. = 6Simplify. The area of the rectangle is 6 m 2. (continued) Area: Parallelograms LESSON 10-1 Additional Examples

8. PRE-ALGEBRA Find the area of each parallelogram. a.b. A = bharea formula = (8)(2)Substitute. = 16Simplify. The area is 16 m 2.The area is 15 in. 2. A = bh = (2.5)(6) = 15 Area: Parallelograms LESSON 10-1 Additional Examples

9. PRE-ALGEBRA Find each area. 1.rectangle ABFE 2.parallelogram ACFD 3.a rectangle with a base of 50 cm and a height of 5 cm 250 cm 2 40 cm 2 48 cm 2 Area: Parallelograms LESSON 10-1 Lesson Quiz