SECTION 11.1

AREAS of RECTANGLES and SQUARES

WARM UP 1) Find the area and perimeter of a square that is 5 inches long.

A = 5 · 5 = 25 2) The area of a square is 64 cm 2 . What is the perimeter?

3) The perimeter of a square is 28 inches. What is the area?

PERIMETER •

TO FIND PERIMETERS

•

Add all the side lengths together!

Area of SQUARES

• Area of a square = sides 2 =

s 2

A

2 2   4 9 2 3

Area of RECTANGLES

•

A = bh or A = lw

•

Base x height length x width

A

 4 2 3

A

 8 3

Find the area and perimeter.

6 2 4 5

P A



A A

 24 10 5  2

w

 2

P

 Remember you can only combine “like” radicals!

NOTE: It is a rectangle.

Give the expression for the area and perimeter.

A = 2x(x – 3) A = 2x 2 – 6x That is as far as you can go!

x - 3 P = 2(x – 3) + 2(2x) P = 2x – 6 + 4x P = 6x – 6 2x NOTE: It is a rectangle.

5 3 30 0

Find the area and perimeter.

10

60 

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

A

  

A

 25 3

P

  

P

 5

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

x

.

a) ⅔ b) 7 c) 8

x = 8

d) 40 e) 59

½x 2x - 1 A = bh 60 = (2x – 1)(

½x)

60 = x 2 – ½x 0 = x 2 – ½x – 60 0 = x 2 – ½x – 60

Real Life Applications

• How much will it cost to blacktop the driveway shown if blacktopping costs $11.00 per square meter? HINT: ADD A LINE!!!!

HINT: You are finding area!

12 m

A = 5(6) = 30 6 m 5 m

9m 4 m

TOTAL AREA = 72 + 30 = 102 m 2 A = 4(18) = 72 TOTAL COST = 4 m

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

.

A = 24(16) = 384 m 2

2 m 2 m

A = 20(12) = 240 m 2 20 m 24 m 12 m

2 m

16 m

2 m

PRACTICE

• Page 426 • #2 – 12

EVENS

•

#23, 24

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