2) congruent base
-An isosceles trapezoid is a trapezoid with congruent base angles and congruent non-parallel sides.
3) opposite angles are complementary
- The base angles have the same measure. The segment that joins the midpoints of the parallel sides is perpendicular to them. Opposite angles are supplementary, which in turn implies that isosceles trapezoids are cyclic quadrilaterals.
4) congruent legs
- The legs are congruent by definition.
