UNIT 9

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CORNELL NOTES HEADER

Topic: Geometry 6th Grade (Unit 9 pg. 1)

E. Q.: How can applying geometric formulas help solve real world problems?

Name: _____________________________Date: _____________________________Class: _____________________________

Chp. 2 Lesson 2 – Perimeter and Area

VOCABULARY

perimeter –

The distance around a figure, measured in linear units i.e. ft., in., m.

 

area –

The amount of surface a figure covers, measured in square units.

PERIMETER OF A RECTANGLE

Perimeter of a Rectangle: P = 2l + 2w

where l = length w = width

 

Ex. A carnival is going to be held in your school’s parking lot. How much rope is needed to enclose the carnival if the parking lot is 200 ft. by 100 ft.?

 

200 ft.

100 ft. P = 2l + 2w

= 2(200) + 2(100)

= 400 + 200

= 600 ft.

AREA OF A RECTANGLE

Area of a Rectangle: A = lw

where l = length w = width

 

Ex. What is the area of the school’s parking lot?

 

200 ft.

100 ft. A = lw

= 200(100)

= 20,000 ft2

PERIMETER OF A SQUARE

Perimeter of a Square: P = 4s where s = length of side

 

Ex. Find the perimeter of the softball diamond with a side length of 60 ft.

 

60 ft.

60 ft. P = 4s

= 4(60)

= 240 ft.

AREA OF A SQUARE

Area of a Square: A = s2 where s = length of side

 

Ex. Find the area of the softball diamond.

 

60 ft.

60 ft. A = s2

= (60)2

= 3,600 ft.2

 

 

 

SOLVING FOR AN UNKNOWN DIMENSION

Write and solve an equation to find the width of a rectangle. Its area is 195 square meters and its length is 15 meters.

 

A = lw

195 = 15w (Substitute in known values into the formula.)

195 = 15w (Divide both sides by 15 to find the value of w.)

15 15

13 m = w The rectangle is 13 m wide.

 

 

 

THE KEY TO SOLVING GEOMETRY PROBLEMSFormula

(write the formula for the perimeter, area, volume, etc. of the shape)

Fill in

(fill in the known values)

Solve

(solve for the unknown value)