Theorem 7.2 Class 9 Maths Explanation with Proof

In this post, we will discuss theorem 7.2 class 9 Maths which is related to Chapter 7 Triangles Class 9 Mathematics. After understanding theorem 7.2, you can solve the exercise questions given in the NCERT book of Class 9 Maths.

 

Theorem 7.2 Class 9

Angles opposite to equal sides of an isosceles triangle are equal.

Proof of Theorem 7.2

We have been given an isosceles triangle ABC in which AB=AC. We need to prove that ∠B=∠C.

Let us draw the bisector of ∠A and let D be the point of intersection of this bisector of ∠A and BC .

In ∆BAD and ∆CAD,

AB=AC (given)             

∠BAD=∠CAD (by construction)

AD=AD (common)

So,  ∠ABD=∠ACD(By SAS rule)

Since they are corresponding angles of congruent triangles.

So, ∠B=∠C.

Related Topics 

1. Theorem 7.1

2. Exercise 7.1

3. Theorem 7.3

If you are looking for theorem 7.2 class 9 in Hindi, please visit - myrbse.in