Question

ABC is an isoceles triangle with AB=AC.Draw AP is perpendicular BC to show that angle B is equal to angle C?

Answer 1

IN Δ ABP and ACP 

AP=AP
AB = AC(given)
∠APB = ∠APC = 90°

so by RHS rule ΔABP = ΔACP 

⇒∠B = ∠C 

OR 

as AB =AC 
∠B = ∠C ( angles opp. to equal sides are equal )