Download Find Perimeter

Find Perimeter
Objective Find the perimeter of polygons.
CA Standards
KEY MG 1.3 Find the
perimeter of a polygon with
integer sides.
MG 1.0 Students choose
and use appropriate units and
measurement tools to quantify
the properties of objects.
Also NS 2.0, KEY NS 2.1 ,
KEY MG 2.1 , KEY MG 2.3 ,
MR 2.0, MR 2.3, MR 2.4
perimeter
length
width
The Cruz family is moving to
a new neighborhood next
week. Sam and his friends are
making a welcome sign for
the family. They plan to put
yarn around the edge of the
sign as a border.
32 in.
The length of the sign is
32 inches. The width is
20 inches. How many inches
of yarn do they need in all?
20 in.
To solve this problem, you
need to find the perimeter .
Example
To find the perimeter, add the measurements of the sides.
20 + 32 + 20 + 32 = 104
The perimeter of the sign is 104 inches.
Solution: The friends need 104 inches of yarn.
Another Example
An octagon is a
plane figure with
8 sides.
To find the perimeter
of this octagon, add
the measurements
of the sides.
IN
IN
IN
IN
IN
IN
IN
IN
6 + 2 + 2 + 2 + 4 + 2 + 4 + 2 = 24 inches
Solution: The perimeter is 24 inches.
Houghton Mifflin California Math, Lesson Transparency 10.2
Copyright © Houghton Mifflin Company. All rights reserved.
Use with Chapter 10, Lesson 2
Find the perimeter of the figure.
FT
1.
FT
2.
IN
IN
3.
FT
FT
MI
MI MI
MI
IN
• What numbers
do I add?
• How should I label
my answer?
MI MI
IN
MI
MI
Guided Problem Solving
Use the questions to solve this problem.
4. Jim is watering his garden. The garden is
the shape of a rectangle. The length of
the garden is 8 feet. The width is 4 feet.
What is the perimeter of Jim’s garden?
a. Understand How many sides are
there? What do you need to find?
b. Plan Draw a picture of the garden.
Label the length of each side.
c. Solve Add the lengths of the sides.
Solve the problem.
____ + ____ + ____ + ____ =
The perimeter of the garden is
feet
feet.
d. Look Back Check your work by adding the
four lengths in a different order. Did you
get the same answer?
Math Talk
Can you find the perimeter of
a square if you know the length of one side?
Why or why not? Explain.
Houghton Mifflin California Math, Lesson Transparency 10.2
Copyright © Houghton Mifflin Company. All rights reserved.
Use with Chapter 10, Lesson 2
Add the lengths of
all the sides to find
the perimeter.