Grade 8 · Unit 1 · गणित

Overlapping & Disjoint Sets

खप्टिएका र अलगिएका समूह — Interactive Digital Lesson

⏱ 45 Minutes 📘 Class 8 📐 Mathematics 🎯 Sets (समूह) 👨‍🏫 Teacher: R. P. Pandey
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Concepts

Start here — understand the core ideas before practising.

What is a Set? (समूह के हो?)

A set is a well-defined collection of distinct objects, called members or elements. We write sets using curly braces { }.

A = {1, 2, 3} B = {a, b, c} C = {चिनी, नुन, मर्च}

Key Vocabulary

Disjoint Sets — अलगिएका समूह

📌 Definition Two sets are disjoint if they share no common element — their intersection is empty: A ∩ B = { } = ∅

Examples

A = {2, 4, 6} and B = {1, 3, 5} — no shared element → Disjoint

P = {a, b} and Q = {c, d} — no shared element → Disjoint

M = {10, 20} and N = {30, 40} — no shared element → Disjoint

🔵 In a Venn diagram, disjoint sets appear as two separate circles that do not touch.

Overlapping Sets — खप्टिएका समूह

📌 Definition Two sets are overlapping if they share at least one common element — their intersection is non-empty: A ∩ B ≠ ∅

Examples

X = {मर्च, नुन, चिनी} and Y = {चिनी, चियापत्ती, दूध} — shared: चिनीOverlapping

A = {1, 2, 3} and B = {3, 4, 5} — shared: 3Overlapping

M = {10, 20} and N = {20, 30} — shared: 20Overlapping

🔵 In a Venn diagram, overlapping sets appear as two circles that partially overlap.

Quick Comparison

Feature Disjoint Sets Overlapping Sets
Common elements None (∅) At least one
Intersection A ∩ B = ∅ A ∩ B ≠ ∅
Venn diagram Separate circles Overlapping circles
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Venn Diagrams

Visual representations of sets — hover circles to explore!

Disjoint Sets

A = {2, 4, 6}  |  B = {1, 3, 5}

U A B 2 4 6 1 3 5 A ∩ B = ∅

No shared elements → Disjoint

Overlapping Sets

A = {1,2,3}  |  B = {3,4,5}

U A B 1 2 3 4 5 A ∩ B = {3}

Shared element: 3Overlapping

🍽️ Real-life Example — Kitchen Sets

X = {मर्च, नुन, चिनी}    Y = {चिनी, चियापत्ती, दूध}

U (Kitchen) X Y मर्च नुन चिनी (shared) चियापत्ती दूध X ∩ Y = {चिनी} → Overlapping Sets

📝 Homework Example

If M = {10, 20} and N = {20, 30} — are they disjoint or overlapping?

MCQ Quiz

10 multiple-choice questions — click an option to answer.

0 / 10
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10/10

Excellent!

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Fill in the Blanks

Type the correct word or symbol in each blank.

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Match the Pairs

Click a term on the left, then click its matching definition on the right. (10 pairs)

Terms

Definitions

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Problem Solving

10 step-by-step worked examples — show or hide each solution!