Options are: CPCTC
Congruent
vertical angles are congruent
If alternate interior angles are congruent then lines are parallel

1) because they are vertical angles

2) because SAS

3)  CPCTC

4) Converse of the Alternate Interior Angles

none of the above.

for one of the equations to be used in the process, there has to be a term in the equation since squared is .

since there is only a term in the first equation, we cannot derive a from completing the square.

solving with completing the square