First, let's illustrate the problem as shown in the picture attached. Then, let's make a two-column proof:
Statement Reason
m∠B = m∠C Given
AB = AC Isosceles Triangle Definition
AK=KB=AH=HC Angle Bisector Postulate
ΔBKC = ΔHBC Line BC is common side
BH = CK Corresponding parts of congruent triangles are congruent