Answer :
Since we have an isosceles triangle, the sides GF and EF are congruent. Therefore, the opposite angles to those sides are congruent too, that is, [tex]m\measuredangle G+m\measuredangle E+m\measuredangle F=180\Rightarrow m\measuredangle F=180-(58+58)\Rightarrow m\measuredangle F=64[/tex]Therefore, the measure of angle F is 64 (option C).