Perimeter of Polygons with Practical Examples

 
 
Lesson 25
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[
OBJECTIVE
]
 
The student will solve problems involving
perimeter of polygons.
[
MY
 
SKILLS
]
 
Multiplication Facts (0 – 9)
 
[
ESSENTIAL
 
QUESTIONS
]
 
1. 
How can the perimeter of a square be found
using a formula?
2. 
How can the perimeter of a rectangle be
found using a formula?
3. 
How can a missing side of a polygon be
determined if  the perimeter of the polygon is
known?
 
SOLVE
 
Margo is helping her dad build a pen in the
backyard for her new puppy. She got the puppy
for her birthday. The pen is in the shape of a
rectangle. The length of the pen is 8 feet, and
the width of the pen is 6 feet. What is the
perimeter of the pen?
 
S
 
Study the Problem
Underline the question.
This problem is asking me to find
the pen’s perimeter.
[Cooperative Pairs]
 
 
P
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A
 
 
P
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B
Investigate Perimeter of Polygons
 
Trace your finger around the edge of your
desktop. This is the 
perimeter
 of the desk.
 
 
What do you think perimeter means?
 
It is the distance around a figure.
 
When might it be useful to know how to
measure the perimeter of any surface?
 
It may be useful when putting up a border
on the bulletin board, or when putting up a
fence in a yard.
Investigate Perimeter of Polygons
Using toothpicks, create a square!
 
 
What do you notice about the square?
 
All of the sides are equal, or the same size.
 
How many sides does the square have?
 
4 sides
Investigate Perimeter of Polygons
Using toothpicks, create a square!
 
How many toothpicks were used to create
the square?
 
4 toothpicks
Investigate Perimeter of Polygons
Using toothpicks, create a square!
 
 
4 units
If each of the toothpicks is considered one
unit of measurement, what is the
perimeter 
or distance around the edge of
the square?
Investigate Perimeter of Polygons
Let’s transfer the toothpick square to the
grid paper and shade.
 
 
4 units
 
What is the perimeter of the square?
 
P 
= 4
units
Investigate Perimeter of Polygons
Add another square by adding 3 more
toothpicks.
 
 
How many units are on the
top of the rectangle?
 
2 units
Investigate Perimeter of Polygons
Add another square by adding 3 more
toothpicks.
 
How many units are on the
bottom of the rectangle?
 
2 units
Investigate Perimeter of Polygons
Add another square by adding 3 more
toothpicks.
 
How many units are on the
left side of the rectangle?
 
1 unit
Investigate Perimeter of Polygons
Add another square by adding 3 more
toothpicks.
 
How many units are on the
right side of the rectangle?
 
1 unit
Investigate Perimeter of Polygons
Add another square by adding 3 more
toothpicks.
 
What is the perimeter of the rectangle?
 
6 units
 
How many squares are in the toothpick
rectangle?
Investigate Perimeter of Polygons
Let’s transfer the toothpick rectangle to the
grid paper and shade.
 
 
2 squares
P 
= 4
units
 
How many units of perimeter are shown for
the shaded rectangle?
 
6 units
 
P 
= 6 units
Investigate Perimeter of Polygons
 
 
Square
 
What is the shape?
 
If Side 1 is the top of the
square, identify the number
of units for this side.
 
2 units
 
Side 1
 
Side 2
 
Side 3
 
Side 4
 
Perimeter
 
1
 
2
 
2
units
Investigate Perimeter of Polygons
 
Square
What is the shape?
If Side 2 is the right side
of the square, identify the
number of units for this
side.
 
2 units
 
1
 
2
2
units
 
2
units
Side 1
Side 2
Side 3
Side 4
Perimeter
Investigate Perimeter of Polygons
 
Square
What is the shape?
If Side 3 is the bottom of
the square, identify the
number of units for this
side.
 
2 units
 
1
 
2
2
units
2
units
 
2
units
Side 1
Side 2
Side 3
Side 4
Perimeter
Investigate Perimeter of Polygons
 
Square
What is the shape?
If Side 4 is the left side of
the square, identify the
number of units for this
side.
 
2 units
 
1
 
2
2
units
2
units
2
units
 
2
units
 
P
 = 2+2+2+2
= 8 units
Side 1
Side 2
Side 3
Side 4
Perimeter
Investigate Perimeter of Polygons
 
 
How is this problem
different from the first
problem?
 
             There are no
units showing inside of
the square, but the
dimensions are given.
4 ft
4 ft
4 ft
4 ft
Side 1
Side 2
Side 3
Side 4
Perimeter
Investigate Perimeter of Polygons
 
 
Identify the units for
this square.
 
Feet
4 ft
4 ft
4 ft
4 ft
 
Describe the sides of
the square.
 
                 They are
all equal.
Side 1
Side 2
Side 3
Side 4
Perimeter
Investigate Perimeter of Polygons
 
 
Identify the measure of
each side to find the
perimeter of the square.
 
4 ft
 
P
 = 4+4+4+4
= 16 feet
 
4 ft
 
4 ft
 
4 ft
 
4 ft
 
4 ft
 
4 ft
 
4 ft
Side 1
Side 2
Side 3
Side 4
Perimeter
Investigate Perimeter of Polygons
 
Square
The shape is a:
 
In this problem, we don’t have a picture,
but we have dimensions. How can we find
the perimeter?
 
P
 = 6+6+6+6
= 24 m
6 m
6 m
6 m
6 m
 
Add all of the dimensions given to find the
perimeter of this square.
Side 1
Side 2
Side 3
Side 4
Perimeter
Missing Sides
 
 
How is the problem different
from the other problems?
P
 = 12 m
3 m
5 m
 
The perimeter is given,
but we are missing a
side.
3 m
5 m
___ m
Side 1
Side 2
Side 3
Perimeter
Missing Sides
 
 
Identify the number of
meters for Side 1.
P
 = 12 m
3 m
5 m
 
3 meters
3 m
5 m
___ m
 
Identify the number of
meters for Side 2.
 
5 meters
Side 1
Side 2
Side 3
Perimeter
Missing Sides
 
 
What is the sum of the
known sides?
P
 = 12 m
3 m
5 m
 
3 meters + 5 meters = 8 meters
3 m
5 m
___ m
 
How can we find the missing
side?
 
Add the two sides, then
subtract from the perimeter.
Side 1
Side 2
Side 3
Perimeter
Missing Sides
 
P
 = 12 m
3 m
5 m
3 m
5 m
___ m
 
12 – 8 = 4 meters
Side 3 = 4 meters
P
 = 3 + 5 + 4 = 12 meters
 
4 m
Side 1
Side 2
Side 3
Perimeter
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
 
What does length mean?
 
how long an object is
 
What is the length of the
rectangle?
 
4 units
Picture
 
4 units
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
What does width mean?
 
how wide an object is
 
What is the width of the
rectangle?
 
1 unit
Picture
4 units
 
1 unit
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
How did you find the
perimeter of the rectangles in
the last activity?
 
We added each side
together to find the total,
or sum.
Picture
4 units
1 unit
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
What is the total length of
the top and bottom of the
rectangle?
 
8 units
Picture
4 units
1 unit
 
How did you determine the
total length?
 
                   Multiply the
top or bottom length by 2
or double one length.
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
What is the total width of
the two sides of the
rectangle?
 
2 units
Picture
4 units
1 unit
 
How did you determine the
total width?
 
                   Multiply one
side length by 2, or double
one width.
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
Can you think of a way to
find the perimeter of the
rectangle using what you
know about the length and
the width?
Picture
4 units
1 unit
 
Multiply the length by 2.
Multiply the width by 2.
Add the products together.
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
What letters might represent
the perimeter, length and
width?
Picture
4 units
1 unit
 
P
 for perimeter
l
 for length
w
 for width
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
 
Can you think of a way to
describe finding the
perimeter using the letters
in a 
formula
?
Picture
4 units
1 unit
 
P
 = 2
l
 + 2
w
 
P
 = 2
l
 + 2
w
 
P
 = 2(4)+2(1)
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
Picture
4 units
1 unit
 
P
 = 2(4) + 2(1)
P
 = 2
l
 + 2
w
P
 = 2(4)+2(1)
 
P
 = 8 + 2
 
P
 = 10 units
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
 
How did you find the
perimeter of the rectangles in
the previous activity?
 
We added each side
together to find the total,
or sum.
Picture
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
How can we find the
perimeter of the square using
only the length of one side?
Picture
 
Multiply one side by 4,
because each of the 4 sides
measures 3 units.
 
3 units
 
3 units
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
Picture
What letters might represent
the perimeter and side.
 
P
 for perimeter
s
 for side
3 units
3 units
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
Picture
Establish a way to describe
finding the perimeter using
one side length, beginning
with 
P
 =.
 
P
 = 4
s
3 units
3 units
 
P
=4
s
 
P
=4(3)=12 units
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
Picture
 
Even though we only know
one side of the figure, what
do we know about a
square?
 
The square has
four equal sides and
four equal angles.
5 in.
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
Picture
If the length of the square
is 5 inches, what is the
width?
 
5 inches
5 in.
 
5 inches
 
5 inches
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
Picture
What formula will we use to
find the perimeter of the
square?
 
P
 = 4
s
5 in.
5 inches
5 inches
 
P
 = 4
s
 
P
 = 4(5)
 
P
 = 4(5)
 
P
 = 20 inches
 
P
 = 20in.
Rectangles and Square Using Formulas
 
Length
Width
Perimeter
Picture
Could we use the formulas
for finding the perimeter of
a triangle or trapezoid?
5 in.
5 inches
5 inches
P
 = 4
s
P
 = 4(5)
P
 = 20in.
 
No, because a triangle has 3
sides, and they are not
always equal. A trapezoid
has sides that are different
lengths and widths.
Perimeter and Area Foldable
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Perimeter and Area Foldable
Perimeter and Area Foldable
Perimeter and Area Foldable
Perimeter and Area Foldable
Perimeter and Area Foldable
Perimeter and Area Foldable
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Perimeter
of
Polygons
Definition
Perimeter and Area Foldable
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Example
 
Example
Perimeter and Area Foldable
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Perimeter
of
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Definition
 
Perimeter
of Polygons
Using
Formulas
Perimeter and Area Foldable
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“Perimeter
of
Polygons
Using
Formulas”
Info
Under This
Flap
Perimeter
of
Polygons
Definition
SOLVE
 
 
Margo is helping her dad build a pen in the
backyard for her new puppy. She got the puppy
for her birthday. The pen is in the shape of a
rectangle. The length of the pen is 8 feet, and
the width of the pen is 6 feet. What is the
perimeter of the pen?
S
 
Study the Problem
Underline the question.
This problem is asking me to find
the pen’s perimeter.
 
 
 
Margo is helping her dad build a pen in the
backyard for her new puppy. She got the puppy
for her birthday. The pen is in the shape of a
rectangle. The length of the pen is 8 feet, and
the width of the pen is 6 feet. What is the
perimeter of the pen?
 
O
 
Organize the Facts
Identify the facts.
Eliminate the unnecessary facts.
List the necessary facts.
 
 
P
e
n
 
i
s
 
a
 
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t
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l
e
 
 
L
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g
t
h
 
i
s
 
8
 
f
e
e
t
 
 
W
i
d
t
h
 
i
s
 
6
 
f
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e
t
 
L
 
Line Up a Plan
 
Choose an operation or operations.
 
Addition, Multiplication
 
Write in words what your plan of action will
be.
 
Multiply the length by two and multiply the
width by two.
 
Then add these values together.
 
V
 
Verify Your Plan with Action
Estimate your answer.
About 30 feet
Carry out your plan.
2 (8)  + 2 (6)
  16   +   12
    28 feet
 
 
 
E
 
Examine Your Results
Does your answer make sense?
(compare your answer to question.)
Yes, because I am looking for the perimeter
of the pen.
Is your answer reasonable?
(compare your answer to the estimate.)
Yes, because it is close to my estimate of
about 30 feet.
 
Is your answer accurate?
(check your work.)
Yes.
Write your answer in a complete sentence.
The perimeter of the pen is 28 feet.
[
ESSENTIAL
 
QUESTIONS
]
 
1.
How can the perimeter of a square be
found using a formula?
 
(Use the formula 
P
 = 4
s
, and substitute
the value of one side for the 
s
. Multiply
four times the value of one side to find
the perimeter.)
[
ESSENTIAL
 
QUESTIONS
]
 
 
2. How can the perimeter of a rectangle be
found using a formula?
 
(Use the formula 
P 
= 2
l
 + 2
w
, and
substitute the value of the length for 
l
 and
the value of the width for 
w
. Multiply the
length by 2 and the width by 2 and then
add the two values to find the perimeter.)
[
ESSENTIAL
 
QUESTIONS
]
 
3.
How can the missing side of a polygon be
determined if the perimeter of the
polygon is known?
 
(Add the values of the given sides and
subtract the sum from the total
perimeter.)
 
Perimeter
Formula
Units
Length
Width
Side
 
 
Lesson 25
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Join Margo in solving real-world problems involving perimeter of polygons. Learn how to find the perimeter of shapes like rectangles and squares through engaging activities and investigate the concept of perimeter in a hands-on manner. Discover essential questions and practical applications of measuring perimeter in everyday scenarios.

  • Perimeter Polygons
  • Practical Examples
  • Real-World Problems
  • Hands-On Learning
  • Geometry Concepts

Uploaded on Sep 19, 2024 | 0 Views


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  1. Lesson 25 Perimeter of Polygons

  2. [OBJECTIVE] The student will solve problems involving perimeter of polygons.

  3. [MYSKILLS] Multiplication Facts (0 9)

  4. [ESSENTIALQUESTIONS] 1. How can the perimeter of a square be found using a formula? 2. How can the perimeter of a rectangle be found using a formula? 3. How can a missing side of a polygon be determined if the perimeter of the polygon is known?

  5. SOLVE Margo is helping her dad build a pen in the backyard for her new puppy. She got the puppy for her birthday. The pen is in the shape of a rectangle. The length of the pen is 8 feet, and the width of the pen is 6 feet. What is the perimeter of the pen? S Study the Problem Underline the question. This problem is asking me to find the pen s perimeter.

  6. [Cooperative Pairs] Partner A Partner B

  7. Investigate Perimeter of Polygons Trace your finger around the edge of your desktop. This is the perimeter of the desk. What do you think perimeter means? It is the distance around a figure. When might it be useful to know how to measure the perimeter of any surface? It may be useful when putting up a border on the bulletin board, or when putting up a fence in a yard.

  8. Investigate Perimeter of Polygons Using toothpicks, create a square! What do you notice about the square? All of the sides are equal, or the same size. How many sides does the square have? 4 sides

  9. Investigate Perimeter of Polygons Using toothpicks, create a square! How many toothpicks were used to create the square? 4 toothpicks

  10. Investigate Perimeter of Polygons Using toothpicks, create a square! If each of the toothpicks is considered one unit of measurement, what is the perimeter or distance around the edge of the square? 4 units

  11. Investigate Perimeter of Polygons Let s transfer the toothpick square to the grid paper and shade. P = 4 units What is the perimeter of the square? 4 units

  12. Investigate Perimeter of Polygons Add another square by adding 3 more toothpicks. How many units are on the top of the rectangle? 2 units

  13. Investigate Perimeter of Polygons Add another square by adding 3 more toothpicks. How many units are on the bottom of the rectangle? 2 units

  14. Investigate Perimeter of Polygons Add another square by adding 3 more toothpicks. How many units are on the left side of the rectangle? 1 unit

  15. Investigate Perimeter of Polygons Add another square by adding 3 more toothpicks. How many units are on the right side of the rectangle? 1 unit

  16. Investigate Perimeter of Polygons Add another square by adding 3 more toothpicks. What is the perimeter of the rectangle? 6 units

  17. Investigate Perimeter of Polygons Let s transfer the toothpick rectangle to the grid paper and shade. P = 4 units P = 6 units How many squares are in the toothpick rectangle? 2 squares How many units of perimeter are shown for the shaded rectangle? 6 units

  18. Investigate Perimeter of Polygons What is the shape? Side 1 Side 2 Side 3 Side 4 2 units Square Perimeter 1 2 If Side 1 is the top of the square, identify the number of units for this side. 2 units

  19. Investigate Perimeter of Polygons What is the shape? Side 1 Side 2 Side 3 Side 4 Square Perimeter 2 2 units units If Side 2 is the right side of the square, identify the number of units for this side. 2 units 1 2

  20. Investigate Perimeter of Polygons What is the shape? Side 1 Side 2 Side 3 Side 4 Square Perimeter 2 2 2 units units units If Side 3 is the bottom of the square, identify the number of units for this side. 2 units 1 2

  21. Investigate Perimeter of Polygons What is the shape? Side 1 Side 2 Side 3 Side 4 Square Perimeter 2 2 2 2 P = 2+2+2+2 = 8 units units units units units If Side 4 is the left side of the square, identify the number of units for this side. 2 units 1 2

  22. Investigate Perimeter of Polygons Perimeter Side 1 Side 2 Side 3 Side 4 4 ft How is this problem different from the first problem?There are no units showing inside of the square, but the dimensions are given. 4 ft 4 ft 4 ft

  23. Investigate Perimeter of Polygons Perimeter Side 1 Side 2 Side 3 Side 4 4 ft Identify the units for this square. Feet 4 ft 4 ft Describe the sides of the square. They are all equal. 4 ft

  24. Investigate Perimeter of Polygons Perimeter Side 1 Side 2 Side 3 Side 4 P = 4+4+4+4 = 16 feet 4 ft 4 ft 4 ft 4 ft 4 ft Identify the measure of each side to find the perimeter of the square. 4 ft 4 ft 4 ft

  25. Investigate Perimeter of Polygons The shape is a: Side 1 Side 2 Side 3 Side 4 Square Perimeter P = 6+6+6+6 = 24 m 6 m 6 m 6 m 6 m In this problem, we don t have a picture, but we have dimensions. How can we find the perimeter? Add all of the dimensions given to find the perimeter of this square.

  26. Missing Sides Perimeter Side 1 Side 2 Side 3 P = 12 m 3 m 5 m How is the problem different from the other problems? The perimeter is given, but we are missing a side. 5 m 3 m ___ m

  27. Missing Sides Perimeter Side 1 Side 2 Side 3 P = 12 m 3 m 5 m Identify the number of meters for Side 1. 3 meters Identify the number of meters for Side 2. 5 meters 5 m 3 m ___ m

  28. Missing Sides Perimeter Side 1 Side 2 Side 3 P = 12 m 3 m 5 m What is the sum of the known sides? 3 meters + 5 meters = 8 meters How can we find the missing side? Add the two sides, then subtract from the perimeter. 5 m 3 m ___ m

  29. Missing Sides Perimeter Side 1 Side 2 Side 3 P = 12 m 3 m 5 m 4 m 12 8 = 4 meters Side 3 = 4 meters P = 3 + 5 + 4 = 12 meters 5 m 3 m ___ m

  30. Rectangles and Square Using Formulas Perimeter Length Width 4 units What does length mean? how long an object is Picture What is the length of the rectangle? 4 units

  31. Rectangles and Square Using Formulas Perimeter Length Width 4 units 1 unit What does width mean? how wide an object is Picture What is the width of the rectangle? 1 unit

  32. Rectangles and Square Using Formulas Perimeter Length Width 4 units 1 unit How did you find the perimeter of the rectangles in the last activity? Picture We added each side together to find the total, or sum.

  33. Rectangles and Square Using Formulas Perimeter Length Width 4 units 1 unit What is the total length of the top and bottom of the rectangle? 8 units Picture How did you determine the total length? Multiply the top or bottom length by 2 or double one length.

  34. Rectangles and Square Using Formulas Perimeter Length Width 4 units 1 unit What is the total width of the two sides of the rectangle? 2 units Picture How did you determine the total width? Multiply one side length by 2, or double one width.

  35. Rectangles and Square Using Formulas Perimeter Length Width 4 units 1 unit Can you think of a way to find the perimeter of the rectangle using what you know about the length and the width? Multiply the length by 2. Multiply the width by 2. Add the products together. Picture

  36. Rectangles and Square Using Formulas Perimeter Length Width 4 units 1 unit What letters might represent the perimeter, length and width? P for perimeter l for length w for width Picture

  37. Rectangles and Square Using Formulas Perimeter P = 2l + 2w P = 2(4)+2(1) Length Width 4 units 1 unit Can you think of a way to describe finding the perimeter using the letters in a formula? P = 2l + 2w Picture

  38. Rectangles and Square Using Formulas Perimeter P = 2l + 2w P = 2(4)+2(1) Length Width 4 units 1 unit P = 2(4) + 2(1) P = 8 + 2 P = 10 units Picture

  39. Rectangles and Square Using Formulas Perimeter Length Width How did you find the perimeter of the rectangles in the previous activity? Picture We added each side together to find the total, or sum.

  40. Rectangles and Square Using Formulas Perimeter Length Width 3 units 3 units How can we find the perimeter of the square using only the length of one side? Picture Multiply one side by 4, because each of the 4 sides measures 3 units.

  41. Rectangles and Square Using Formulas Perimeter Length Width 3 units 3 units What letters might represent the perimeter and side. Picture P for perimeter s for side

  42. Rectangles and Square Using Formulas Perimeter P=4s P=4(3)=12 units Length Width 3 units 3 units Establish a way to describe finding the perimeter using one side length, beginning with P =. P = 4s Picture

  43. Rectangles and Square Using Formulas Perimeter Length Width Even though we only know one side of the figure, what do we know about a square? The square has four equal sides and four equal angles. Picture 5 in.

  44. Rectangles and Square Using Formulas Perimeter Length Width 5 inches 5 inches If the length of the square is 5 inches, what is the width? Picture 5 in. 5 inches

  45. Rectangles and Square Using Formulas Perimeter P = 4s P = 4(5) P = 20in. Length Width 5 inches 5 inches What formula will we use to find the perimeter of the square? P = 4s P = 4(5) P = 20 inches Picture 5 in.

  46. Rectangles and Square Using Formulas Perimeter P = 4s P = 4(5) P = 20in. Length Width 5 inches 5 inches Could we use the formulas for finding the perimeter of a triangle or trapezoid? No, because a triangle has 3 sides, and they are not always equal. A trapezoid has sides that are different lengths and widths. Picture 5 in.

  47. Perimeter and Area Foldable `

  48. Perimeter and Area Foldable

  49. Perimeter and Area Foldable

  50. Perimeter and Area Foldable

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