SECTION 11.1

AREAS of RECTANGLES and

SQUARES

WARM UP

1) Find the area and perimeter of a square

that is 5 inches long.

2) The area of a square is 64 cm2. What is

the perimeter?

3) The perimeter of a square is 28 inches.

What is the area?

A = 5 · 5 = 25P = 5 + 5 + 5 + 5 = 20

A = 64, 8 = sideP = 8 + 8 + 8 + 8 = 32 cm

P = 28, 28/4 = 7A = 7 · 7 = 49 in2

PERIMETER

• TO FIND PERIMETERS

• Add all the side lengths together!

Area of SQUARES

• Area of a square = sides2 = s2

22

3A

72

3

22 4

3 9

2

3

Area of RECTANGLES

• A = bh or A = lw

• Base x height length x width

4

2 3

72

3

4 2 3A

8 3A

Find the area and perimeter.A bh

4 5 6 2A

4 6 5 2A

6 2

4 5

NOTE: It is a rectangle.

24 10A

2 2 2 4 5 2 6 2P l w

8 5 12 2P Remember you can only combine “like” radicals!

Give the expression for the area and perimeter.

x - 3

2xNOTE: It is a rectangle.

A = 2x(x – 3)

A = 2x2 – 6x

That is as far as you can go!

P = 2(x – 3) + 2(2x)

P = 2x – 6 + 4x

P = 6x – 6

10

60

Find the area and perimeter.

5 3

5 5 3A

25 3A

HINT: It’s a special right triangle! I love these guys!

300

5

2(5) 2 5 3P

10 10 3P

SAT Problem• The area of the rectangle is 60 square units.

Find the value of x.

a) ⅔b) 7

c) 8

d) 40

e) 59

2x - 1½x

A = bh

60 = (2x – 1)( x)½

60 = x2 – ½x

0 = x2 – ½x – 60

0 = x2 – ½x – 60This is UGLY. Try to Guess and Test.

x = 8

Real Life Applications

• How much will it cost to blacktop the

driveway shown if blacktopping costs

$11.00 per square meter?

12 m 9m

18 m

4 m

HINT: ADD A LINE!!!!

HINT: You are finding area!6 m

5 m

4 m

A = 5(6) = 30

A = 4(18) = 72

TOTAL AREA = 72 + 30 = 102 m2

TOTAL COST = 102(11) = $1,122

Draw a picture

• A path 2 m wide surrounds a rectangular

garden 20 m long and 12 m wide. Find the

area of the PATH.

2 m

20 m

12 mA = 20(12) = 240 m2

A = 24(16) = 384 m2

2 m

2 m

2 m

24 m

16 m

Total Area - Garden384 – 240 = 144 m2

PRACTICE

• Page 426

• #2 – 12 EVENS

• #23, 24

Area Video

• Don’t you just love these videos!!!!