# _2-16-11_ Lesson 10-3 Area of Parallelograms _Class 2 Notes_ by dandanhuanghuang

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```									10-3 Area of Parallelograms

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Warm Up
California Standards
Lesson Presentation

Holt CA Course 1
10-3 Area of Parallelograms

Holt CA Course 1
10-3 Area of Parallelograms

Holt CA Course 1
10-3 Area of Parallelograms

Holt CA Course 1
10-3 Area of Parallelograms

Holt CA Course 1
10-3 Area of Parallelograms

Warm Up
Find each product.

1. 8  12          96
56
2. 3 1  5 1          or 18 2
2       3    3       3
3. 9.4  6.3       59.22
4. 3.5  7         24.5

Holt CA Course 1
10-3 Area of Parallelograms

California
Standards
AF3.1 Use variables in expressions
describing geometric quantities (e.g.,
P = 2w + 2l, A = 1bh, C = pd–the formulas
2
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

Holt CA Course 1
10-3 Area of Parallelograms

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

Holt CA Course 1
10-3 Area of Parallelograms

Vocabulary
area
base
height

Holt CA Course 1
10-3 Area 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.           Area = 15 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              h
is the same as the width.                   b

Holt CA Course 1
10-3 Area of Parallelograms

Holt CA Course 1
10-3 Area of Parallelograms
Example 1: Finding the Area of a Parallelogram

Find the area of the parallelogram.

8m

16 m

The area of the parallelogram is 128 m2.

Holt CA Course 1
10-3 Area of Parallelograms
Check It Out! Example 2

Find the area of the parallelogram.

6 cm

12 cm

SMART Response Que
To set the properties right click and select
SMART Response Question Object->Properties...

The area of the parallelogram
is 72 cm2.

Holt CA Course 1
10-3 Area of Parallelograms

SMART Response Quiz Results (Correct answer:72)
Skipped
4%

72
96%

Holt CA Course 1
10-3 Area of Parallelograms
Example 3: Finding the Area of a Rectangle

Find the area of the rectangle.

4.5 in.

7.4 in.

The area of the rectangle is 33.3 in2.

Holt CA Course 1
10-3 Area of Parallelograms
Check It Out! Example 4

Find the area of the rectangle.

6.3 in.

8.2 in.

SMART Response Que
To set the properties right click and select
SMART Response Question Object->Properties...

The area of the rectangle
is 51.66 in2.

Holt CA Course 1
10-3 Area of Parallelograms

SMART Response Quiz Results (Correct answer:51.66)
33.26
49.86    4%
50.36
4%
4%
57.66
4%

52.92
4%
50.84
5%
516.6
5%

51.66
70%

Holt CA Course 1
10-3 Area of Parallelograms
Example 5: Finding Length or
Width of a Rectangle
The area of a playing field is 1,470 ft2 and the
length is 42 ft. What is the width of the field?

The width of the playing
field is 35 ft.

Holt CA Course 1
10-3 Area of Parallelograms
Check It Out! Example 6
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?

SMART Response Que
To set the properties right click and select
SMART Response Question Object->Properties...

The length of the
parking lot is 51 ft.

Holt CA Course 1
10-3 Area of Parallelograms

SMART Response Quiz Results (Correct answer:51)

Skipped
3500    61     9%
4%     4%

37.42
5%

51
78%

Holt CA Course 1
10-3 Area of Parallelograms
Example 7: Measurement Application
A carpenter is laying a wood floor measuring
4 yd by 5 yd. How many square feet of
flooring material does she need?

Step 1: Draw and label a diagram.
4 yd
Step 2: Convert the units.
5 yd

Holt CA Course 1
10-3 Area of Parallelograms
Example 7 Continued
A carpenter is laying a wood floor measuring
4 yd by 5 yd. How many square feet of flooring
material does she need?
Step 3: Find the area of the floor in square feet.
A = lw   Use the formula for the
area of a rectangle.                  12 ft

15 ft

The carpenter needs 180 ft2
of flooring material.

Holt CA Course 1
10-3 Area of Parallelograms
Check It Out! Example 8
A carpenter is laying a tile floor measuring 5
yd by 7 yd. How many square feet of tile
material does she need?
5 yd
Step 1: Draw and label a diagram.
7 yd
Step 2: Convert the units.

Holt CA Course 1
10-3 Area of Parallelograms
Check It Out! Example 8 Continued
A carpenter is laying a tile floor measuring 5
yd by 7 yd. How many square feet of tile
material does she need?

Step 3: Find the area of the tile                           15 ft
floor in square feet.
21 ft
A = lw

SMART Response Que
To set the properties right click and select
SMART Response Question Object->Properties...

The carpenter needs 315 ft2
of flooring material.

Holt CA Course 1
10-3 Area of Parallelograms

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Lesson Videos

Holt CA Course 1
10-3 Area of Parallelograms
Lesson Quiz: Part I
Find each perimeter.
1.              2.
9 cm
5
__
4 6 ft

3. What is the perimeter of a polygon with
side lengths of 15 cm, 18 cm, 21 cm, 32
cm, and 26 cm?
112 cm

Holt CA Course 1
10-3 Area of Parallelograms
Lesson Quiz
Find the circumference of each circle. Use
3.14 as an estimate for p.
1.                   2.

C ≈ 25.12            C ≈ 18.84
in.                  in.

3. Find the circumference of a circle with
diameter of 20 feet. Use 3.14 as an
estimate C ≈ 62.8 p.
t for ft

Holt CA Course 1
10-3 Area of Parallelograms
Lesson Quiz: Part I

Find the area of each figure.      105      1
or 13 in2
8       8
1.                          2.

24.5 ft2

3.                          4.
57 or
2
84 ft2                   28 1 ft2
2

Holt CA Course 1
10-3 Area 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

Holt CA Course 1

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