Answer
1) $ \angle $EAB $\cong$ $\angle$ EBA
2) $\triangle$ ABCis isosceles
Work Step by Step
It is already given that
1) ABCD is an isosceles trapezoid
Furthermore
2) $\angle$ EAB $\cong$ $\angle $EBA as from trapezoid theorem the base angle of isosceles trapezoid are $\cong$
Therefore;
3) $\triangle$ ABC is isosceles $\triangle$ as it have the congruent base angles
