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Chapter 6 of 16
Revision Notes

Triangles

Maharashtra Board · Class 9 · Mathematics

Quick revision notes for Triangles — Maharashtra Board Class 9 Mathematics. Key concepts, formulas, and definitions for last-minute revision.

45 questions25 flashcards5 concepts

Key Topics to Revise

1

Remote Interior Angles Theorem

  • An exterior angle of a triangle equals the sum of its two remote interior angles
  • Remote interior angles are the two angles of the triangle that are not adjacent to the exterior angle
  • An exterior angle is always greater than either remote interior angle
2

Congruence of Triangles

  • Two triangles are congruent if they have the same shape and size
  • Congruent triangles have all corresponding sides and angles equal
  • Four main tests for congruence: SAS, ASA, SSS, and Hypotenuse-Side test
3

Isosceles Triangle Theorems

  • In an isosceles triangle, angles opposite to equal sides are equal
  • If two angles of a triangle are equal, then sides opposite to them are equal
  • These theorems are converses of each other
4

Special Right Triangles

  • 30°-60°-90° triangle: sides are in ratio 1:√3:2
  • 45°-45°-90° triangle: sides are in ratio 1:1:√2
  • These ratios help in quick calculations without using trigonometry

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Full Notes

Key Concepts

The measure of an exterior angleTwo triangles are congruent if theyIn an isosceles triangle30°A median connects a vertex

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Frequently Asked Questions

What are the important topics in Triangles for Maharashtra Board Class 9 Mathematics?

Triangles covers several key topics that are frequently asked in Maharashtra Board Class 9 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.

Start by understanding all key concepts. Practise previous year questions from this chapter. Revise formulas and definitions regularly. Use flashcards for quick revision before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.