The primary sector involves activities that:

produce goods directly from nature

Which of these belongs to the secondary sector?

Manufacturing cloth from cotton in a factory

What is the perimeter of a closed figure?

It is the distance covered along the boundary in one complete round, equal to the sum of the lengths of all its sides.

What is the formula for the perimeter of a rectangle?

Perimeter \(= 2 \times (\text{length} + \text{breadth})\).

What is the perimeter of a square of side \(s\)?

Perimeter \(= 4 \times s\), four times the length of one side.

What is the area of a rectangle?

Area \(= \text{length} \times \text{breadth}\).

How is the area of a right triangle related to a rectangle?

A diagonal splits a rectangle into two equal triangles, so a right triangle\u2019s area is half the area of the rectangle, i.e. half of base \(\times\) height.

How can you estimate the area of an irregular shape?

Place it on squared or graph paper; count each full square as 1 unit, ignore parts less than half, count more than half as 1, and a half square as \(\tfrac{1}{2}\).

Can two figures with the same area have different perimeters?

Yes; for example different rectangles with area 24 square units can have very different perimeters.

Find the width of a rectangular garden 25 m long with area 300 sq m.

Width \(= 300 \div 25 = 12\) m.

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Perimeter and Area — Class 6 Mathematics

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Mathematics · 10 chapters

Summary, key terms, important questions and a practice quiz with AI diagnosis for each.

CBSE Class 6Mathematics Ganita Prakash

Chapter 6: Perimeter and Area

Summary

This chapter studies perimeter and area of plane figures. The perimeter of any closed figure is the distance covered along its boundary in one round; for a polygon it is the sum of all side lengths. The perimeter of a rectangle is \(2 \times (\text{length} + \text{breadth})\), of a square is \(4 \times \text{side}\), and of a triangle is the sum of its three sides; a regular polygon\u2019s perimeter is the number of sides times the length of a side. Area is the amount of region enclosed by a closed figure, measured in square units. The area of a rectangle is length \(\times\) breadth and the area of a square is side \(\times\) side. The chapter shows how to estimate areas of irregular shapes using squared or graph paper, counting full squares and half squares. A key result is that the area of a triangle is half the area of the rectangle that contains it, so the area of a right triangle is half of base \(\times\) height. Through tangram puzzles, house plans and area mazes, students see that two figures can have the same area but different perimeters, or the same perimeter but different areas.

Perimeter of PolygonsPerimeter of Rectangles, Squares and TrianglesArea and Square UnitsArea of Rectangle and SquareEstimating Area with GridsArea of a Triangle

Key terms

Perimeter

The total distance along the boundary of a closed figure, i.e. the sum of all its side lengths.

Area

The amount of region enclosed by a closed figure, measured in square units.

Perimeter of a rectangle

Twice the sum of length and breadth: \(2 \times (l + b)\).

Perimeter of a square

Four times the length of a side: \(4 \times \text{side}\).

Area of a rectangle

Length multiplied by breadth: \(l \times b\).

Square unit

The unit of area, equal to the area of a \(1 \times 1\) square, such as a square centimetre or square metre.

Important questions

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Perimeter

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The total distance along the boundary of a closed figure, i.e. the sum of all its side lengths.

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Practice quiz · Perimeter and Area

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Perimeter and Area

Maths 10 Qs · ~10 min