Chapter 6 · Class IX Mathematics · NCERT Exercises

Lines and Angles — Exercises

Angle Pairs, Parallel Lines & Angle Sum — Both Exercises Fully Solved

📂 2 Exercises 📝 12 Questions 🎓 Moderate

▶ Start Exercises 📖 Revise Notes

Exercise Index

Complementary and supplementary angles; linear pair; vertically opposite angles; intersecting lines

6 Q Easy-Moderate

Parallel lines and transversal; alternate interior angles; co-interior angles; corresponding angles; angle sum in triangle

2 exercise files · 12 total questions

Chapter at a Glance

CBSE BoardsNTSEOlympiad

11 Concepts

8 Formulas

Moderate Difficulty

8–10% Weightage

Before You Begin

Prerequisites

✓Basic angle measurement
✓Types of angles (Class VI)
✓Parallel and perpendicular lines

Have Ready

🔧Protractor
🔧Ruler
🔧Parallel lines diagram card

Exercise Topic Map

Exercise 6.1 Linear pair: supplementary + adjacent; vertically opposite angles are equal; identify angle pairs at intersection

Exercise 6.2 Parallel lines + transversal: alternate angles equal; co-interior angles supplementary; corresponding angles equal; use triangle angle sum = 180°

Key Formulae — Recall Before Solving

\(\angle AOB + \angle BOC = 180° \quad \text{(Linear Pair)}\)

\(\angle AOC = \angle BOD \quad \text{(Vertically Opposite Angles)}\)

\(\text{Alternate interior angles equal} \iff \text{lines are parallel}\)

\(\angle A + \angle B + \angle C = 180° \quad \text{(Angle sum of triangle)}\)

NCERT Solving Method

Step 1 — Linear pair: two angles on a straight line; always sum to 180°. Step 2 — Vertically opposite: formed at intersection of two lines; always equal. Step 3 — Parallel lines: identify the transversal; name the angle pair (alternate/co-interior/corresponding); apply the relevant property. Step 4 — Proof format: write Given, To Prove, Construction (if needed), Proof; cite each reason. Step 5 — Exterior angle of triangle = sum of two non-adjacent interior angles (useful shortcut).

Continue Your Preparation

📖NotesTheory & concepts 🧠MCQsTopic-wise practice ⚖️True–FalseConcept check ➡️Next ChapterTriangles

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NCERT Class 9 Maths Lines and Angles Solutions

NCERT Class 9 Maths Lines and Angles Solutions — Complete Notes & Solutions · academia-aeternum.com

🎓 Class 9 📐 Mathematics 📖 NCERT ✅ Free Access 🏆 CBSE · JEE

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