We have been given that PQ bisects . In the second statement of the given two-column proof, the statement is .
This implies that the two angles formed by bisection of angle by the line PQ are equal. We know that the reason for this is simple. It is the definition of bisection of an angle that the two smaller angles formed will be equal to each other.
Therefore, the reason for statement 2 of the given two column proof is c) Definition of bisect
