bisector AD of angle BAC of triangle ABC passes through the centre O of the circumcircle of triangle ABC ,prove that AB = AC

Question

Answer it urgently 

Answer 1

AO=BO=CO definition of circumcircle which is enter of the circle that passes through all three vertices of the triangle.

triangle ABO congruent to triangle AOC

because of side and two angles ASA

angle ABO=BAO=CAO=OCA

so AB=AC from congruence of triangles