These Perimeter and Area revision notes sum up the whole sixth chapter of the new Ganita Manjari book in one place. Our perimeter and area class 9 maths notes explain the perimeter of plane shapes, the circumference of a circle, arcs and sectors, and the area of every common figure in plain language.
- What they cover: perimeter, circumference, arcs and sectors, and the area of common shapes.
- Who they help: Class 9 students who want a fast, clear revision before a test.
- Why they save time: every formula and key rule sits on one short page.
These notes are prepared by subject teachers, matched to the current 2026-27 NCERT Ganita Manjari book, and written so a Class 9 student can revise the whole chapter quickly.
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Table of Contents |
What Do Class 9 Maths Perimeter and Area Notes Cover?
The perimeter and area class 9 maths notes cover the full chapter in short, simple parts. You first learn the difference between perimeter and area, then the perimeter formulas for squares, rectangles, and triangles. Next you meet the circumference of a circle, the number π, and arcs and sectors. The notes end with the area of rectangles, parallelograms, triangles, and circles, plus composite shapes.
Video Walkthrough
Source: Vedantu CBSE 10th on YouTube
Perimeter and Area Class 9 Maths Topic-by-Topic Summary
Here is a short summary of each main topic. Read one part at a time and try a quick example as you go.
Perimeter and Circumference
Perimeter is the total length of the boundary of a shape, and its unit is a plain length like cm or m. For a square of side a, the perimeter is 4a. For a rectangle it is 2(l + b), and for an equilateral triangle it is 3a. A regular polygon with n sides has perimeter na. A circle has no straight sides, so its boundary is called the circumference. It is C = 2π r = π d. The constant π is the ratio of circumference to diameter, about 3.14 or 227.
Arcs, Sectors, and the Number Pi
An arc is a part of the circumference, and a sector is the pie-shaped region between two radii and an arc. An arc that makes an angle θ at the centre has length 2π r × θ360. A semicircular arc is π r and a quarter-circle arc is π r2. The perimeter of a sector is the arc plus the two radii, so it is 2π r × θ360 + 2r. The number π is irrational, since its decimal never ends and never repeats. Fractions like 227 are only close values.
Area of Common Shapes
Area is the flat surface a shape covers, and its unit is a square unit like cm². A rectangle has area l × b and a square has area a2. A parallelogram has area base times height, where the height is the perpendicular distance, not the slant side. A triangle is half of its matching rectangle, so its area is 12bh. A circle has area π r2, which uses the radius, not the diameter. For composite shapes, split them into known parts, then add the areas or subtract a cut-out.
Key Points and Results to Remember in Perimeter and Area
These are the must-know formulas from the chapter. Keep this short list handy for last-minute revision.
| Point | What it means |
|---|---|
| Rectangle perimeter | 2(l + b); square perimeter is 4a. |
| Circumference | 2π r = π d for a circle of radius r. |
| Arc length | 2π r × θ360 for a central angle θ. |
| Triangle area | 12bh, which is half of a rectangle. |
| Parallelogram area | Base times perpendicular height, b × h. |
| Circle area | π r2, using the radius. |
How to Revise Perimeter and Area Quickly
To revise fast, skim the perimeter and area class 9 maths notes above, then write the perimeter and area formula for each shape from memory. Next, work one circumference sum and one circle-area sum using π = 227. This short loop fixes the chapter. The time you need depends on whether this is a revision or a first read.
Revision mode
1-2 hours
If you have done this chapter once and are revising.
First-read
4-6 hours
If you are learning Perimeter and Area for the first time.
How will Collegedunia's Notes Help You with Perimeter and Area?
Collegedunia gives you these perimeter and area class 9 maths notes as one clean revision page that matches the new book exactly. You get the formulas, the units, and the common traps together, so revision is quick.
- 2026-27 book match: Every formula follows the new Ganita Manjari chapter, not the old syllabus.
- Plain language: Short sentences and simple words make each rule easy to read.
- Formulas in one box: The perimeter and area rules sit together for fast recall.
- Free PDF: Download the notes and revise offline before your annual exam.
More Perimeter and Area Maths Class 9 Resources
NCERT Notes for Class 9 Maths: All Chapters
Use the table below to open the NCERT Notes for any other chapter of the new Class 9 Maths book.
| Chapter | Resource |
|---|---|
| Chapter 1 | Coordinates Notes |
| Chapter 2 | Linear Polynomials Notes |
| Chapter 3 | The World of Numbers Notes |
| Chapter 4 | Algebraic Identities Notes |
| Chapter 5 | Circles Notes |
| Chapter 6 | Perimeter and Area Notes |
| Chapter 7 | Introduction to Probability Notes |
| Chapter 8 | Sequences and Progressions Notes |
Perimeter and Area Class 9 Maths Notes FAQs
Ques. Where can I download the Perimeter and Area Class 9 Maths Notes PDF?
Ans. You can download the Perimeter and Area Class 9 Maths Notes PDF directly from this page. Both the Normal and HD versions are free.
Ques. How many pages are the Perimeter and Area Class 9 Maths Notes?
Ans. The notes run to about 22 pages. They cover every perimeter and area formula, arcs and sectors, and composite shapes with clear diagrams.
Ques. Is Perimeter and Area part of the new Class 9 Maths book?
Ans. Yes. Perimeter and Area is Chapter 6 of the new Ganita Manjari book for the 2026-27 syllabus. It covers plane shapes and the circle.
Ques. What is the difference between perimeter and area?
Ans. Perimeter is the length of the boundary, measured in units like cm. Area is the surface inside the shape, measured in square units like cm².
Ques. Are these notes enough to revise the full chapter?
Ans. Yes. The notes list every formula and common mistake, so they work well for a quick revision before the exam.
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