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Tamil Nadu (TNBSE)Class 6 Mathematics★ 6-10 marks in the TN Class 6 Term 3 exam through perimeter and area sums

Perimeter and Area

Samacheer Kalvi (TN State Board) Class 6 Maths — Term 3 Chapter 3, Perimeter and Area. The perimeter and area of a square, a rectangle and a triangle, and the perimeter and area of combined figures, with worked examples, exercises and quick revision.

⏱ 14 min readEasy difficulty✓ Free · NCERT-aligned

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By the end of this chapter you'll be able to…

1Define perimeter and area with units
2Find the perimeter and area of a square
3Find the perimeter and area of a rectangle
4Find the area of a triangle
5Find the area of combined figures

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Why this chapter matters

Perimeter and area of basic shapes are everyday mensuration skills used in fencing, flooring and land measurement. They are directly tested in the TN Class 6 Term 3 exam.

Before you start — revise these

A 5-minute refresher here will save you 30 minutes of confusion below.

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Class 5 — Area and Perimeter

Squares and rectangles.

Perimeter and Area — Class 6 Maths (Samacheer Kalvi)

TN State Board (Samacheer Kalvi) Class 6 Mathematics, Term 3 — Chapter 3. Measuring boundaries and surfaces.

1. About this chapter

This chapter covers the perimeter and area of a square, rectangle and triangle, and the perimeter and area of combined figures.

2. Perimeter and area

Perimeter is the total length of the boundary (in cm, m).
Area is the amount of surface enclosed (in cm², m²).

3. Formulae

Shape	Perimeter	Area
Square (side s)	4s	s × s = s²
Rectangle (l, b)	2(l + b)	l × b
Triangle (base b, height h)	sum of the three sides	½ × b × h

4. Combined figures

For a combined figure, split it into known shapes (squares, rectangles, triangles), find each area, and add them; the perimeter is the total length of the outer boundary.

5. Worked examples

Example 1. Find the perimeter and area of a square of side 6 cm. Perimeter = 4 × 6 = 24 cm; Area = 6 × 6 = 36 cm².

Example 2. Find the area of a rectangle 8 cm by 5 cm. 8 × 5 = 40 cm².

Example 3. Find the area of a triangle with base 10 cm and height 6 cm. ½ × 10 × 6 = 30 cm².

6. Exercises (Samacheer Kalvi)

Find the perimeter and area of a square of side 9 cm.
A rectangle is 12 m long and 7 m wide. Find its perimeter and area.
Find the area of a triangle with base 14 cm and height 8 cm.
The area of a square is 49 cm². Find its side and perimeter.
A figure is made of a 4 cm × 4 cm square joined to a 4 cm × 2 cm rectangle. Find the total area.

7. Common mistakes

Mistake: Mixing up perimeter and area. Fix: Perimeter = boundary length (cm); area = surface (cm²).
Mistake: Forgetting the ½ in the triangle area. Fix: Triangle area = ½ × base × height.
Mistake: Using slant side instead of height for a triangle. Fix: Use the perpendicular height for the area.

8. Quick revision

Term 3 · Ch 3 · perimeter and area.
Square: perimeter 4s, area s²; rectangle: perimeter 2(l + b), area l × b; triangle: area ½ × b × h.
Perimeter is in linear units; area in square units.
Combined figures: split into known shapes, add the areas; perimeter = outer boundary.

Key formulas & results

Everything you need to memorise, in one card. Screenshot this for revision.

Square

perimeter = 4s; area = s²

Side s.

Rectangle

perimeter = 2(l + b); area = l × b

Length and breadth.

Triangle

area = ½ × base × height

Perpendicular height.

Combined figure

split into shapes, add areas

Perimeter = outer boundary.

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Common mistakes & fixes

These are the exact errors that cost students marks in board exams. Read them once, save yourself the trouble.

WATCH OUT

✗ Mixing up perimeter and area

✓ Perimeter = boundary length (cm); area = surface (cm²).

WATCH OUT

✗ Forgetting the ½ in the triangle area

✓ Triangle area = ½ × base × height.

WATCH OUT

✗ Using the slant side instead of the height for a triangle

✓ Use the perpendicular height for the area.

NCERT exercises (with solutions)

Every NCERT exercise from this chapter — what it covers and how many questions to expect.

Square and rectangle

Perimeter and area sums.

Questions

Triangle

Area from base and height.

Questions

Combined figures

Total area and perimeter.

Questions

Practice problems

Try each one yourself before tapping "Show solution". Active recall > rereading.

Q1EASY· Square

Find the perimeter and area of a square of side 6 cm.

▶ Show solution

Perimeter 24 cm; area 36 cm².

Q2EASY· Rectangle

Find the area of a rectangle 8 cm by 5 cm.

▶ Show solution

40 cm².

Q3EASY· Triangle

Find the area of a triangle with base 10 cm and height 6 cm.

▶ Show solution

30 cm².

Q4MEDIUM· Reverse

The area of a square is 49 cm². Find its side and perimeter.

▶ Show solution

Side = 7 cm; perimeter = 28 cm.

Q5MEDIUM· Rectangle

A rectangle is 12 m long and 7 m wide. Find its perimeter and area.

▶ Show solution

Perimeter 2(12 + 7) = 38 m; area 84 m².

Q6MEDIUM· Combined

A 4×4 cm square is joined to a 4×2 cm rectangle. Find the total area.

▶ Show solution

16 + 8 = 24 cm².

5-minute revision

The whole chapter, distilled. Read this the night before the exam.

•Term 3 Chapter 3 of Samacheer Kalvi Class 6 Maths.
•Perimeter = boundary length (linear units); area = surface (square units).
•Square: perimeter 4s, area s²; rectangle: perimeter 2(l + b), area l × b.
•Triangle area = ½ × base × height (use the perpendicular height).
•For combined figures, split into known shapes and add the areas.
•The perimeter of a combined figure is the length of its outer boundary.

Tamil Nadu (TNBSE) marks blueprint

Where the marks come from in this chapter — so you can plan your prep.

Typical chapter weightage: 6-10 marks across perimeter and area

Question type	Marks each	Typical count	What it tests
Square/rectangle	2	2	Perimeter and area
Triangle	1-2	1	Area
Combined/reverse	2	1	Total area or finding the side

Prep strategy

Write the formula before substituting
Use square units for area
Include the ½ for triangles
Split combined figures into known shapes

Where this shows up in the real world

This chapter isn't just an exam topic — it lives in the world around you.

Fencing

Perimeter gives the length of fence needed.

Flooring

Area gives the amount of tiles or carpet.

Land

Plots are measured by area.

Exam strategy

Battle-tested tips from teachers and toppers for this chapter.

State the formula first
Keep area in square units
Remember ½ for triangles
Add areas for combined figures

Going beyond the textbook

For olympiad aspirants and curious learners — topics that build on this chapter.

A rectangle and a square have the same perimeter of 24 cm; compare their areas.
Find the area of an L-shaped figure given its dimensions.

Where else this chapter is tested

CBSE board isn't the only one — other exams test this chapter too.

TN Class 6 Term 3 ExamHigh

NMMS / Foundation MathsMedium

School unit testsHigh

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Questions students ask

The real ones — pulled from the Q&A community and tutor sessions.

Perimeter is the total length around the edge of a shape (measured in cm or m), while area is the amount of flat surface it covers (measured in square units like cm²).

Divide it into simple shapes such as squares, rectangles and triangles, find the area of each, and add them all together.

Practice more, ask doubts, find a tutor

Tamil Nadu (TNBSE) Class 6 mock tests

Tamil Nadu (TNBSE) Class 6 PYQs

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Mathematics flashcards

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