Holt CA Course 1

10-3Area of Parallelograms

Warm Up

California Standards

Lesson Presentation

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Holt CA Course 1

10-3Area of Parallelograms

Warm UpFind each product.

1. 8 12

2. 3

3. 9.4 6.3

4. 3.5 7

96

59.22

12

513

24.5

1823

56 3 or

Holt CA Course 1

10-3Area of Parallelograms

AF3.1 Use variables in expressions describing geometric quantities (e.g.,P = 2w + 2l, A = bh, C = d–the formulas for the perimeter of a rectangle, the area of a triangle, and the circumference of a circle, respectively).Also covered: NS2.1, AF1.1, AF2.1, AF3.2

California Standards

1 2

Holt CA Course 1

10-3Area of Parallelograms

Objective:Objective: You will learn how You will learn how to (YWLHT) find the area of to (YWLHT) find the area of rectangles and other rectangles and other parallelograms.parallelograms.

Holt CA Course 1

10-3Area of Parallelograms

Vocabulary

area

base

height

Holt CA Course 1

10-3Area of Parallelograms

The area of a figure is the number of non-overlapping unit squares needed to cover the figure. Area is measured in square units.

The base of a parallelogram is the length of one side. Its height is the perpendicular distance from the base to the opposite side.

For a rectangle, the base is the same as the length, and the height is the same as the width.

h

b

Area = 15 square units

Holt CA Course 1

10-3Area of Parallelograms

Holt CA Course 1

10-3Area of Parallelograms

Find the area of the parallelogram.

Example 1: Finding the Area of a Parallelogram

8 m

16 m

The area of the parallelogram is 128 m2.

Holt CA Course 1

10-3Area of Parallelograms

Find the area of the parallelogram.

6 cm

12 cm

The area of the parallelogram is 72 cm2.

Check It Out! Example 2

SMART Response QuestionTo set the properties right click and selectSMART Response Question Object->Properties...

Holt CA Course 1

10-3Area of Parallelograms

Find the area of the rectangle.

Example 3: Finding the Area of a Rectangle

4.5 in.

7.4 in.

The area of the rectangle is 33.3 in2.

Holt CA Course 1

10-3Area of Parallelograms

Find the area of the rectangle.

6.3 in.

8.2 in.

The area of the rectangle is 51.66 in2.

Check It Out! Example 4

SMART Response QuestionTo set the properties right click and selectSMART Response Question Object->Properties...

Holt CA Course 1

10-3Area of Parallelograms

The area of a playing field is 1,470 ft2 and the length is 42 ft. What is the width of the field?

Example 5: Finding Length or Width of a Rectangle

The width of the playing field is 35 ft.

Holt CA Course 1

10-3Area of Parallelograms

The area of a rectangular parking lot is 3,570 ft2 and the width is 70 ft. What is the length of the parking lot?

Check It Out! Example 6

The length of the parking lot is 51 ft.

SMART Response QuestionTo set the properties right click and selectSMART Response Question Object->Properties...

Holt CA Course 1

10-3Area of Parallelograms

A carpenter is laying a wood floor measuring 4 yd by 5 yd. How many square feet of flooring material does she need?

Example 7: Measurement Application

Step 1: Draw and label a diagram.

Step 2: Convert the units.4 yd

5 yd

Holt CA Course 1

10-3Area of Parallelograms

A carpenter is laying a wood floor measuring 4 yd by 5 yd. How many square feet of flooring material does she need?

Example 7 Continued

Step 3: Find the area of the floor in square feet.

A = lw Use the formula for the area of a rectangle.

The carpenter needs 180 ft2

of flooring material.

12 ft

15 ft

Holt CA Course 1

10-3Area of Parallelograms

A carpenter is laying a tile floor measuring 5 yd by 7 yd. How many square feet of tile material does she need?

Check It Out! Example 8

Step 1: Draw and label a diagram.

Step 2: Convert the units.

5 yd

7 yd

Holt CA Course 1

10-3Area of ParallelogramsCheck It Out! Example 8 Continued

Step 3: Find the area of the tile floor in square feet.

A = lw

A carpenter is laying a tile floor measuring 5 yd by 7 yd. How many square feet of tile material does she need?

15 ft

21 ft

The carpenter needs 315 ft2

of flooring material.

SMART Response QuestionTo set the properties right click and selectSMART Response Question Object->Properties...

Holt CA Course 1

10-3Area of Parallelograms

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Holt CA Course 1

10-3Area of Parallelograms

Lesson Quiz: Part I

Find each perimeter.

1. 2.

3. What is the perimeter of a polygon with

side lengths of 15 cm, 18 cm, 21 cm, 32

cm, and 26 cm?

9 cm

4 ft

112 cm

56__

Holt CA Course 1

10-3Area of ParallelogramsLesson Quiz

Find the circumference of each circle. Use 3.14 as an estimate for .

1. 2.

3. Find the circumference of a circle with

diameter of 20 feet. Use 3.14 as an

estimate t for .

C ≈ 25.12 in.

C ≈ 18.84 in.

C ≈ 62.8 ft

Holt CA Course 1

10-3Area of ParallelogramsLesson Quiz: Part I

Find the area of each figure.

1. 2.

3.

24.5 ft2

84 ft2

4.

1318

in2105 8 or

28 12

ft2

572

or

Holt CA Course 1

10-3Area of Parallelograms

Lesson Quiz: Part II

5. Diego is building a rectangular platform measuring 36 in. by 54 in. What is the area of the platform in square feet?

13.5 ft2