Key Learning Outcomes
By the end of this chapter, “Perimeter and Area”, readers will:
- Understand the meaning of Perimeter and Area
- Identify and differentiate between Perimeter and Area
- Apply formulas to find the Perimeter and Area of basic shapes
- Use correct units of measurement
- Relate mathematical concepts to real life
- Solve word problems
- Develop problem-solving and visualization skills
- Build practical mathematical understanding
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Introduction
Have you ever tried putting a fence around your garden or carpeting your room and wondered how much material you’ll need?
That’s where Perimeter and Area come in!
In simple words,
- Area tells us the space inside a shape (the surface it covers).
- Perimeter tells us the distance around a shape (the boundary).
These two concepts are like best friends in mathematics — they often appear together but have totally different meanings.
Let’s explore these two concepts step by step in a fun and easy way — just like your smart friend explaining maths in class!
What is Perimeter?
Perimeter means the total distance around the boundary of a closed figure.
or
The perimeter is the total length of all sides of a closed shape.
In simpler words, if you walk all the way around the edge of a shape — that distance is its perimeter.
Formula:
For different shapes, the perimeter formula changes a little:
- Rectangle: 2 × (Length + Breadth)
- Square: 4 × Side
- Triangle: Sum of all three sides
- Circle: 2 × π × Radius (but you’ll learn this in higher classes)
Example:
If a rectangle has a length of 8 cm and a breadth of 5 cm,
then,
Perimeter = 2 × (8 + 5) = 26 cm.
That means the total boundary of the rectangle is 26 cm long.
Real-Life Connection:
Imagine you’re putting a fence around your rectangular garden. You need to know the perimeter to buy the right length of fencing wire.
| Shape | Formula | Example |
|---|---|---|
| Square | 4 × side | If side = 5 cm → 4 × 5 = 20 cm |
| Rectangle | 2 × (Length + Breadth) | 2 × (8 + 6) = 28 cm |
| Triangle | Sum of all sides | 4 + 5 + 6 = 15 cm |
| Circle | 2πr (Circumference) | If radius = 7 cm → 2 × 3.14 × 7 = 43.96 cm |
Takeaway:
- Perimeter helps us measure how much boundary a shape has.
- Whenever you need to fence a park, decorate a border, or measure a frame, you are finding its perimeter!
What is Area?
Area is the amount of space covered by a shape or surface.
Imagine spreading a mat on the floor — the total surface it covers is its area.
or
If you spread a mat, lay tiles, or paint a wall — you’re covering an area.
Formula:
For common shapes,
- Circle: π × Radius² (for higher classes)
- Rectangle: Area = Length × Breadth
- Square: Area = Side × Side
- Triangle: (½) × Base × Height
Example:
If a rectangular garden has a length of 8 m and a breadth of 5 m,
Area = Length × Breadth = 8 × 5 = 40 m² (square meters)
That means the garden covers 40 square meters of land.
Real-Life Connection:
When you want to paint a wall or cover your floor with tiles, you need to know its area — not perimeter!
| Shape | Formula | Example |
|---|---|---|
| Square | Side × Side | If side = 5 cm → 5 × 5 = 25 cm² |
| Rectangle | Length × Breadth | 8 × 6 = 48 cm² |
| Triangle | ½ × Base × Height | ½ × 6 × 4 = 12 cm² |
| Circle | πr² | 3.14 × 7 × 7 = 153.86 cm² |
Takeaway:
- Area tells us how much surface a shape covers.
- Whenever you need to paint a wall, lay tiles, or grow grass, you calculate the area — because you’re covering the surface.
Difference Between Perimeter and Area:
| Feature | Perimeter | Area |
|---|---|---|
| Meaning | Distance around a shape | Space inside a shape |
| Measurement Unit | cm, m, km | cm², m², km² |
| Example | Fencing a park | Covering the park with grass |
| Formula (Rectangle) | 2 × (L + B) | L × B |
Finding Perimeter and Area of Common Shapes:
1. Square
A square has all sides equal.
- Perimeter: 4 × Side
- Area: Side × Side
Example:
Side = 6 cm
Perimeter = 4 × 6 = 24 cm
Area = 6 × 6 = 36 cm²
2. Rectangle
A rectangle has opposite sides equal.
- Perimeter: 2 × (Length + Breadth)
- Area: Length × Breadth
Example:
Length = 10 cm, Breadth = 4 cm
Perimeter = 2 × (10 + 4) = 28 cm
Area = 10 × 4 = 40 cm²
3. Triangle
- Perimeter: Sum of all sides
- Area: (½) × Base × Height
Example:
Sides = 3 cm, 4 cm, 5 cm
Perimeter = 3 + 4 + 5 = 12 cm
If base = 4 cm and height = 3 cm,
Area = ½ × 4 × 3 = 6 cm²
Real-Life Uses of Perimeter and Area:
| Activity | What You Find | Example |
|---|---|---|
| Building a fence | Perimeter | Around your school playground |
| Laying carpet or tiles | Area | Inside your classroom |
| Decorating a photo frame | Perimeter | Border length needed |
| Painting a wall | Area | Surface to paint |
| Making a garden bed | Both | Fence length and soil area |
Quick Recap Formulas:
| Shape | Perimeter | Area |
|---|---|---|
| Square | 4 × side | side × side |
| Rectangle | 2 × (L + B) | L × B |
| Triangle | a + b + c | ½ × base × height |
| Circle | 2πr | πr² |
Quick Tips to Remember:
- Perimeter = Outside boundary
- Area = Inside space
- Always use the same units (like cm or m).
- For area, write units as square (cm², m²).
- Practice with real-life objects, such as notebooks, windows, or floors.
Fun Facts
- The unit for area is always written with a square (²) symbol because it covers two dimensions — length and breadth.
- Farmers use area to measure their fields, while architects use perimeter to design boundary walls!
Summary
So, in short:
- Perimeter measures the boundary.
- Area measures the surface inside.
- Both are super useful in our daily life — from decorating a room to planning a park!
Before buying materials like:
- Wire, rope, or border stones → find Perimeter.
- Tiles, paint, or grass → find Area.
This small step can save you time, money, and effort!
If you understand how to use both correctly, you’ll find many real-world problems easy to solve — and math will become one of your favorite subjects!
Practice Questions:
A. Fill In The Blanks.
- The total distance around a figure is called its ____________.
- The amount of surface covered by a figure is called its ____________.
- The area of a rectangle is given by ____________.
- The perimeter of a square is ____________.
- The standard unit of area is ____________.
Answers
- Perimeter
- Area
- Length × Breadth
- 4 × Side
- Square metre (m²)
B. Match The Following.
| Column A | Column B |
|---|---|
| 1. Square | a. 2 × (length + breadth) |
| 2. Rectangle | b. 4 × side |
| 3. Triangle | c. Sum of all sides |
| 4. Circle | d. 2 × π × radius |
Answers
- b
- a
- c
- d
C. Short Answer Questions.
- What is the difference between perimeter and area?
- Find the perimeter of a rectangle whose length is 12 m and breadth is 8 m.
- Find the area of a square whose side is 9 m.
- The sides of a triangle are 8 cm, 10 cm, and 12 cm. Find its perimeter.
- A rectangular park is 50 m long and 40 m wide. Find its area.
Answers
- Difference between Perimeter and Area:
- Perimeter is the total distance around a shape.
- Area is the amount of surface a shape covers.
- Perimeter of rectangle (12 m × 8 m): Perimeter = 2 × (12 + 8) = 40 m
- Area of square (side 9 m): Area = 9 × 9 = 81 m²
- Perimeter of triangle (8, 10, 12): Perimeter = 8 + 10 + 12 = 30 cm
- Area of rectangle (50 m × 40 m): Area = 50 × 40 = 2000 m²
D. Word Problem
- A farmer wants to fence his square field whose side is 25 m. Find the length of the fence required.
- The floor of a classroom is 8 m long and 6 m wide. Find the area of the floor and the cost of polishing it at ₹20 per m².
- A rectangular garden is 30 m long and 20 m wide. Find:
- (a) Its perimeter
- (b) Its area
- A square field has an area of 49 m². Find its perimeter.
Answers
- Square field fencing:
Perimeter = 4 × 25 = 100 m
The farmer needs 100 metres of wire.
2. Classroom floor:
Area = 8 × 6 = 48 m²
Cost = 48 × ₹20 = ₹960
The polishing cost is ₹960.
3. Garden:
(a) Perimeter = 2 × (30 + 20) = 100 m
(b) Area = 30 × 20 = 600 m²
4. Square field (Area = 49 m²):
Side = √49 = 7 m
Perimeter = 4 × 7 = 28 m
E. Higher Thinking Questions
- Two rectangles have the same perimeter but different areas. Can you draw such examples?
- Why is the unit of area written as “square units”?
- Which one changes faster — area or perimeter — when you increase the sides of a shape?
Answers
- Examples:
- Rectangle 8 m × 2 m → Perimeter = 20 m, Area = 16 m²
- Square 5 m × 5 m → Perimeter = 20 m, Area = 25 m²
2. Reason for square units:
Because area is calculated by multiplying two lengths (length × breadth).
3. Area changes faster when dimensions increase — because it’s based on multiplication, not just addition.
Supplementary Materials:
Provide downloadable materials for learners to review:
- – PDF Guide: “Coming Soon”
- – Cheat Sheet: “Coming Soon”
- – Video Source: “JNG ACADEMY“
- – Articles: “Blog Page“

FAQs:
Q1. What is Perimeter?
Q2. What is Area?
Q3. What is the unit of Perimeter and Area?
Perimeter → metre (m), centimetre (cm)
Area → square metre (m²), square centimetre (cm²)
Q4. Why is Area written in square units?
Q5. Can two shapes have the same perimeter but different areas?
Q6. What is the formula for the area of a rectangle?
Q7. What is the formula for the perimeter of a square?
Q8. Why do we need to learn perimeter and area?
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Share Your Valuable Thoughts:
What’s one real-life situation where you used perimeter or area without realizing it?
Share your thoughts in the comments below — or tell your teacher and classmates in class discussion!