# RS Aggarwal Chapter 8 Class 9 Maths Exercises 8.1 (ex 8a) Solutions

RS Aggarwal Chapter 8 Class 9 Maths Exercise 8.1 Solutions: You have studied triangles and their various properties in your earlier classes. You know that a closed figure formed by three intersecting lines is called a triangle. (‘Tri’ means ‘three’). A triangle has three sides, three angles, and three vertices. In this chapter, you will study in detail the congruence of triangles, rules of congruence, some more properties of triangles, and inequalities in a triangle. You have already verified most of these properties in earlier classes. We will now prove some of them.

EXERCISE 8

## Important Definition for RS Aggarwal Chapter 8 Class 9 Maths Ex 8a Solutions

A triangle is a closed geometrical figure formed by three sides and three angles.

1. Two figures are congruent if they have the same shape and same size.
2. If the two triangles ABC and DEF are congruent under the correspondence that A ↔ D, B ↔ E and C ↔ F, then symbolically, these can be expressed as ∆ ABC ≅ ∆ DEF.

Right Angled Triangle: Pythagoras Theorem

Suppose ∆ ABC is a right-angled triangle with AB as the perpendicular, BC as the base and AC as the hypotenuse; then Pythagoras Theorem will be expressed as:

(Hypotenuse)2 = (Perpendicular)2 + (Base)2
i.e. (AC)2 = (AB)2 + (BC)2

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