Final answer:
Statements b) FG and AC are equal, and c) FG and GC are equal, guarantee that FG is perpendicular to AB.
Step-by-step explanation:
To guarantee that FG is perpendicular to AB, statement b) FG and AC are equal, and statement c) FG and GC are equal, must both be true.
If FG and AC are equal, it means that FG is the hypotenuse of a right triangle with sides FG and AC, and AC is perpendicular to FG.
If FG and GC are equal, it means that FG is the hypotenuse of a right triangle with sides FG and GC, and GC is perpendicular to FG.