Question

Subject:- MATHEMATICS

Answer 1

In Δ , ABC right angled at A and AB = AC Hence ∠ A = ∠ B We know that Sum of angles of a triangle = 180º ∠A+ ∠B+ ∠C=180º 90º+∠B+∠B=180º 2∠B=180º -90º 2∠B=90º ∠B=45º………………………………………..(i) ALSO , AD is the bisector of BAC So , ∠BAD = ∠CAD = 90º/2 = 45º …………………………….(ii) ∠BAD = ∠ABC SO, AD = BD ………………………………(iii) . Similarly angle CAD = angle ACD So, AD = DC ………………………………..(iv) adding equation (iii) and (iv) We will get, AD + AD = BD+DC 2AD = BC 

Hope it helps....