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JAC • Class 6 • Mathematics • Ch 12

Estimated Time: 45 Mins

Study Progress: In Progress

Polygons

Distinguish open and closed figures; classify triangles and quadrilaterals.

View All Chapters JCERT Hindi Textbook

Overview Core Concepts Solved Examples Common Traps Summary Self Check Take MCQ Test

Why This Chapter Matters

Distinguish open and closed figures; classify triangles and quadrilaterals.

Before You Begin (Prerequisites)

Familiarity with simple shapes and measurement

What You Will Learn (Core Objectives)

Distinguish open and closed figures; classify triangles and quadrilaterals.

Chapter Roadmap & Progression

1 Syllabus and book alignment

2 Concept 1

3 Concept 2

4 Concept 3

Complete Concept Guide (100% Curriculum Coverage)

Syllabus and book alignment

JCERT 2026–27: Regular schools (Non-SOE) — Chapter 12 · Polygons. Syllabus pages 202–216. These notes follow this topic. Official syllabus. Official JCERT Hindi textbook. Some source PDFs are damaged. The supplementary reference uses different chapter numbering.

Concept 1

A polygon is a simple closed plane figure made of three or more line segments. Its sides meet only at adjacent endpoints. An open figure or a figure with a curved boundary is not a polygon.

Concept 2

A triangle has three sides and three vertices. A scalene triangle has all sides unequal, an isosceles triangle has at least two equal sides, and an equilateral triangle has three equal sides. Classifying by angles gives acute-angled, right-angled and obtuse-angled triangles.

Concept 3

A quadrilateral has four sides. A trapezium has a pair of parallel sides; a parallelogram has both pairs of opposite sides parallel. A rectangle has four right angles. A rhombus has four equal sides. A square has four equal sides and four right angles, so it is both a rectangle and a rhombus.

Conceptual Solved Examples & Case Studies

Example 1

A triangle has sides 5 cm, 5 cm and 8 cm. Classify it by sides.

Step-by-Step Solution:

It is isosceles because two sides are equal. Its perimeter is 5 + 5 + 8 = 18 cm.

Common Misconceptions & Examiner Traps

Common Misconception

Common misconception

Scientific Reality & Correction

A circle is closed but is not a polygon: its boundary is curved.

Chapter Summary & 10 Key Takeaways

Takeaway 1

A polygon is a simple closed plane figure made of three or more line segments. Its sides meet only at adjacent endpoints. An open figure or a figure with a curved boundary is not a polygon.

Takeaway 2

Takeaway 3

Check Your Understanding (Diagnostic Practice Questions)

Diagnostic questions testing core conceptual clarity. Answers are hidden initially — solve each problem first, then click to reveal the step-by-step verified solution.

Is every rectangle a square?

Reveal Answer & Explanation

Answer: No. A rectangle’s adjacent sides need not be equal. Every square is a rectangle.
Use the definition above.

Chapter practice

CBT tests for this chapter are not published yet. Solve the self-check questions above and compare your answers.

All Class 6 Mathematics Chapters

Ch 1: Knowing Our Numbers Ch 2: Whole Numbers Ch 3: Integers Ch 4: Playing with Numbers Ch 5: Fractions Ch 6: Decimals Ch 7: Ratio and Proportion Ch 8: Algebra Ch 9: Line, Line Segment and Ray Ch 10: Pairs of Lines Ch 11: Angles Ch 12: Polygons Ch 13: Circle Ch 14: Three-Dimensional Shapes Ch 15: Symmetry Ch 16: Practical Geometry Ch 17: Perimeter and Area Ch 18: Data Handling

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