CBSE Class 9 Maths | Chapter 2 : Triangles by Abraham | Learn Smarter
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Chapter 2 : Triangles

Triangles are fundamental geometric shapes characterized by three sides, three angles, and three vertices. Congruent triangles possess identical sizes and shapes, established through several congruence criteria including SSS, SAS, ASA, AAS, and RHS. This chapter also delves into triangle properties and inequalities, providing essential insights into the relationships between triangle sides and angles.

Sections

  • 7

    Triangles

    This section covers the fundamental properties of triangles, including types of triangles based on congruence and important inequalities.

    Learning Practice

  • 7.1

    Summary

    This section defines triangles, outlines congruence criteria, and discusses triangle properties and inequalities.

    Learning Practice

  • 7.2

    Congruence Criteria

    The section discusses the definition of congruent triangles and the various criteria used to determine if two triangles are congruent.

    Learning Practice

  • 7.2.1

    Sss (Side-Side-Side)

    This section covers the SSS criterion for triangle congruence, defining congruent triangles and exploring related properties.

    Learning Practice

  • 7.2.2

    Sas (Side-Angle-Side)

    This section discusses the SAS congruence criterion for triangles, which states that if two sides and the included angle of one triangle are equal to those of another triangle, the two triangles are congruent.

    Learning Practice

  • 7.2.3

    Asa (Angle-Side-Angle)

    The ASA (Angle-Side-Angle) theorem states that two triangles are congruent if two angles and the included side of one triangle are equal to two angles and the included side of another triangle.

    Learning Practice

  • 7.2.4

    Aas (Angle-Angle-Side)

    The AAS criterion states that if two angles and a non-included side of one triangle are equal to those of another triangle, the triangles are congruent.

    Learning Practice

  • 7.2.5

    Rhs (Right Angle-Hypotenuse-Side)

    The RHS criterion is a method to prove the congruence of right triangles by comparing the hypotenuse and one side.

    Learning Practice

  • 7.3

    Properties Of A Triangle

    This section covers the fundamental properties of triangles, including congruence criteria and inequalities involving triangles.

    Learning Practice

  • 7.4

    Inequalities In A Triangle

    Inequalities in a triangle refer to the relationships between the lengths of sides and the measures of angles, establishing that the longest side is opposite the largest angle, and that the sum of any two sides exceeds the third.

    Learning Practice

References

Class_9_Maths_Chapter_7_Triangles.pdf

Class Notes

Memorization

What we have learnt

  • A triangle consists of thre...
  • Congruence criteria for tri...
  • Properties of triangles rev...

Final Test

Revision Tests