In Δ ABC, AB = AC and the bisectors of angles B and C intersect at point O. Prove that :
(i) BO = CO
(ii) AO bisects ∠BAC
In ΔABC, AB = AC
⇒ ∠B=∠C [Angles opposite to equal sides are equal]
Also OA and OB are bisectors of angles B and C.
⇒ ∠OBC=∠OCB
∴ OB = OC [Sides opposite to equal angles are equal]
Now consider, Δ AOB and Δ AOC
OA = OA (Common side)
AB = AC (Given)
OB = OC (Proved)
ΔAOB≅ΔAOC [By SSS congruence criterion]
∴∠OAB=∠OAC
That is OA is bisector ∠A.