∠ABC is an isosceles triangle and AB =AC = 2a unit BC = a unit, Draw AD ⊥ BC , and find the length of AD

Explanation

Given that AB=BC=2a units and BC=a units AD⊥BC ⇒ 'D' is midpoint of BC a BD=DC= 2 Here \triangle ABD is a right angled triangle where AB is hypotenuse AB2 =BD2 + AD2 2 2 2 (8) ⇒ AD2 =AB2 − BD a 2 2 ⇒ AD= 2a − 2 a2 4a 2 − 4 = 15a2 4 15 a = = 2 units