Perimeter

1. Perimeter: Measuring the
Distance Around a Shape
Welcome to a fun journey exploring perimeter! We'll use hands-on
activities and real-world examples to understand this important
concept.
by Raj Maitri Jain

2. Concrete Representation of Perimeter
Build and Measure
Create any shape and measure it sides using string.
Walk the Perimeter
Let’s walk around a classroom or playground, counting steps to
find the measurement of its sides.

3. So, Let’s understand Perimeter?
The perimeter of a shape is
defined as the total length
of its boundary.

4. Measuring Perimeter of
Common Shapes
1 Squares
Each side is equal, so we
can multiply the length of
one side by 4.
2 Rectangles
We add the length of all
four sides together.
3 Triangles
Add the lengths of all three sides.

9. WORKSHEE
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13. Understanding Irregular Shapes
What are they?
Shapes that don't have all sides equal or all angles
equal. They can have different lengths and curves.
Examples:
A leaf, a star, a piece of pizza. They have unique and
interesting outlines.

14. Measuring the Sides of an
Irregular Shape
1 1. Use a Ruler
Measure each side
carefully, starting from
one point and going all
the way to the next
point.
2 2. Units of Measurement
Use the same units for
all sides, like
centimeters or inches,
to keep things
consistent.
3 3. Mark Measurements
Write down the length of each side next to it, so you don't forget.

15. Find the perimeter of the given Irregular
Shape

17. Calculating the Perimeter Step-by-Step
1
1. Add All Sides
Sum up the lengths of all the sides of the irregular shape.
2
2. Units Matter
Make sure you include the units (like cm or inches) when you
write the final answer.
3
3. Perimeter
The total length you calculated is the perimeter of
the irregular shape.

18. Strategies for Finding Perimeter
Break it Down
If the shape is complex, divide it
into smaller, simpler shapes.
Then find the perimeter of each
part and add them together.
Visual Aid
Use a ruler to draw a line
around the shape. This helps
visualize the path you need to
measure.
String Method
Wrap a string around the
shape, then measure the
string's length. This is the
perimeter.

19. Common Mistakes and How to Avoid Them
1
Missing a Side
Make sure you measure all sides, don't miss any when adding them up.
2
Incorrect Units
Use the same units for all measurements to avoid confusion. Don't mix cm and inc
3
Forgetting to Add
Remember to add up the lengths of all the sides to
find the total perimeter.

20. Formulas for Calculating Perimeter
Square
P = 4s, where 's' is the length of one
side.
Rectangle
P = 2l + 2w, where 'l' is length and 'w' is
width.
Triangle
P = a + b + c, where 'a', 'b', and 'c' are
the lengths of the sides.

21. Real-World Applications of
Perimeter
Building a Fence
We need to know the perimeter of the area we want to
enclose.
Track and Field
The perimeter of a running track is essential for races.
Home Improvement
Calculating perimeter helps when buying materials for
framing a room.

22. Putting It All Together:
Perimeter in Action
1
Measure
Identify the shape and measure all
the sides.
2
Formula
Choose the appropriate formula
for the shape.
3
Calculate
Substitute the side lengths into the
formula.
4
Perimeter
The result represents the total
distance around the shape.

23. Missing Length
Find the missing length in the following
figure.

24. Missing Length

25. Find the missing length in the following
figure.

26. Find the missing length of the given square.

27. These shapes have been made with 6 squares
& 5
Squares respectively. Find the
perimeter of each. Take each side to be 1 cm.