Given: isosceles trapezoid efgh prove: δfhe ≅ δgeh trapezoid e f g h is shown. Diagonals are drawn from point f to point h and from point g to point e. Sides f g and e h are parallel. It is given that trapezoid efgh is an isosceles trapezoid. We know that fe ≅ gh by the definition of. The base angle theorem of isosceles trapezoids verifies that angle is congruent to angle. We also see that eh ≅ eh by the property. Therefore, by , we see that δfhe ≅ δgeh.