Circumference of a Circle Lesson 10.8. Perimeter the perimeter is the distance around a figure.
Lesson Measure Perimeter
Transcript of Lesson Measure Perimeter
Name
Measure Perimeter
The distance around a dosed figure is called the
Math in My WorldExample 1Berto walked around a park on the rectangularpath shown- How fat did Berto walk?
Opposite sides of a rectangle are equal. So, the side
lengths are 12 yards, 12 yards, 6 yards, and 6 Y&ds.
Add the measures of au of the sides of the figure.
Perimeter 12 yards + 12 yards + 6 yards + 6 yat&
Perimeter =
So, Berto walked
Key Concept
yards
yards.
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Lesson I
ESSENTIAL QUESTIONWhy is to
areal
12 yd
825
.1
Words To God the penmeter 01 a rectangle. odd the lengthsof the The perimeter of a rectangle also equals2 bmes 'ts length plus 2 times its widttv
Content at
A square has four sides of equal length. ro find the perimeterof a square, multip&y the length of one side by four.
Example 2Find the perimeter of a square with
side lengths Of 6 inches.
One Way Add fre measures of all of thesides of the figure.
P 6 inches + 6 inches 6 inches 4 6 inches
P 24 inches
Another Way use a formula
Multip&y the length of one side by 4 because there
are 4 sides of equal length.
s ts equS to one Side length
6 in.
6 in.
6 in.
p x 6 inches
p 24 inches
So, the perimeter of the square is
Guided Practice
Find each perimeter.
g cm
2.
826
inches.
Descrbe two
ways to find the
perimeter of a
square.
Nome
Independent Practice
Find each perimeter.
8 mm
6 mm
8 mm
15 cm
12ft
12ft
12tt
Algebra Find the unknown side Length. Write an equation to find
the perimeter.
10Yd
The unknown side length is
Find the perimeter of each rectangle in units.
4 in.
4 in. ? in.
4 in.
The unknown side length is
Lesson I Meuse Perimeter 827
t) Problem SolvingUse the picture of a footban field for Exercises 11—12.
Wt',at is the petimetet of the foocball field without
the end zones?
12. Each end zone is 10 yards long What is theperimeter of the entire football field in feet?
PRACTICE Use Number Sense A baseballdiamond is shaped Lke a square. The perimeter is
360 lect. What is the length of each side?
14. PRACTICE Explain to a Friend Explain to a
friend how to find the perimeter of the figure Shownto the right
15. Building on the Essential Question How can a formula helpme to find perimeter?
828 Chapter 13 Penmeter and
160
10 ft
Name
Hands OnModel Area
A square with a side length of one unit is calleda unit square.
A unit square has one square unit of area and can beused to measure area Area is the number of square
units needed to CO•eet a figure without overlapping,
Draw It
Find the area of the rectangles shown in the table.
Rectangle I - Length
(units)
Draw each rectangle.
Width
(units) (sq units)
Use grid paper to draw each rectangle.
Find the length and width of each rectangle.Count the number of unit squares frat coyer the length
and width of the rectangle- Record each in the table.
Determine the area Of each rectangle.
Count the number of whole squares that cover
the rectangle. Each whole square is I square unit.
Colire Contert at
Dola
Lesson 3
ESSENTIAL QUESTIONis it important to
measÜe perimeterand area?
Sha&ng. oc covering.o unrt qlt.jore
tn one squate t»ntt
Lessen 3 839
Try It
Find a formula that can be used to find the
area of a rectangle.
Measure the length and width of eachobject listed in the table.
Use a centimeter ruler to measure the
length and the w•dth of eoch object to the
nearest centimeter. Record the results in the table.
Crayons24
length
width
Area
(sq an)
Find the area of each object-
Use what you learned in the first
example to estimate the area of each
Draw rectangles on grid paper.Then count the unit squares to find
the area. Record the results.
Justify the formula for area.
took for a pattem to find how lengthand width relate to area,
I LengthObject
(cm)
sticky mte
box
book
Width
The area of each object is the product of the
and
Talk About It
t. How did you make yout estimates for the orcas of the objectsin Activity 2? How dose were the estimates to the actual areas?
2. Wl•.at operation can you use with the length and the width
to equal the area of a rectangle? Explarn,
S• PRACTICE Use Symbols What s the formula for the area Of arectangle? Use A for area. for length. and w for 'Mdth.
840 Chapter Penn-eter ond
Nerrve
Practice It
Complete the table below.
Rectangle
agnnaa
I Length (units)
o
Width (units)
D
I Area (sq units)
Lesson 3 Cn: Area 841
Apply It
Use the area formula you wrote in Exercise 3
to solve each problem.
9. ML Hart is hangng a pidure on a wall. The pictureframe has a length of 12 inches and a Width of
9 oches. How much wail space wili the picture need?
'O. What is the area of a dassroom with a length
04 30 feet and a width of t S feet?
Miss Foster wants to buy carpet for her living room.
the living room has a length of IS feet and a width
of 10 feet Hcy.v much carpet "ill she need?
12• PRACTICE Use Math Tools Rickfs monitor
is a rectangle. The length is 15 inches and the width is 12 inches.
Estimate the area of the monitor.
Write About It
IS. Suppose two rectangles have the same area. Wast they have the
same length and width? Explain.
842 Area
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Nome
Measure Area
You know that area is the number of sqnre units
needed to cover a region Of figure without any
Math in My WorldExample 1the Perez family wants to put the sandbox
shown in their backyard. mat is the area ofthe sandbox?
One Way Count unit squares.
Tile the rectangle with unn squares. Each '.nit
square has an area of one separe foot.
toft
Dala
Lesson 4
ESSENTIAL Q*STtON
measure
and area?
Another Way Multiply.
Muttiply the length times the width to
find the area.
A length x width
A = 10 feet x S feet
square feet
There are
There are
unit squares.
square feet
So, the area of the sandbox is square feet
i
Key Concept Area ofa Rectangle
To the A Of a rectangle, mulEp(Y the letgth Cby the Width w.
SymbolsW w
Find the measure of the missing side
A = S x S Wute tt•e gormuta.
64 8 x S
Think: 8 times what number equals 64?
meters
The measure of the missing side is
Guided Practice
Find the area of each square or rectangle.
You can also find the area of a square.
Key Concept
1.
Words
Symbols
To find the area A of a square, mult4)ty the lengthot one 9de s by Self.
s
s
s
Example 2The area •nd the measure of one side of the square is given.
meters.
Area 64 sq m
Describe two
ways to find the
area of a sepate.
2. S yd
846 Chapte Pnmeter "d Area
Name
Independent Practice
Find the area Of each square or rectangle.
nan—nana
10 yd
Algebra The area and the measure of one side of each square
ot rectangle are given. Label the missing sides.
847
7 in.
Area — 49 square inches
Area = 5 square centimeters
Area — 32 square meters
6 in.
Area — 24 square inches
Lesson4 Measure Area
t) Problem SolvingEach child in Dixon's class has a
rectangular ru»tebook that has an area
of 108 square inches. If the notebook
is 9 inches w€de, what is the length ofthe
12. A cat is 15 feet long md 6 feet wide, It is parkedon o rectangular driveway with an areo of I t 2 square
feet. How much of the driæ.vay is not coveted bythe car?
IS. PRACTICE Plan Your Solution A rectangularpldtground is 40 meters by 10 meters. Its area will
be cm•ered with shredded tires. Each bag of shredded
tires covers 2(X) quare meters and costs $30 findthe cost for this project
14• PRACTICE Reason A square has sides measuring 3 feet If thesides of a square are doubled, will the area also double? Explain.
IS. Building on the Essential Question How can estimation helpme to find the area of a rectangle ot square?
848 Chapte Penmetet Area