When constructing trapezoid D,E,F,C, I started with circle D and copied it to create circle C. Then the intersection created point A and I created a congruent circle with midpoint A. Then I created points E and F with the intersections of circles D and A, and C and A. Next, I drew line segments EA and FA, this created three equilateral triangles which proved DE's and CF's congruency. Finally, to prove that segment DC and EF are parallel I created circles D' and C' to make the perpendicular bisectors of segments EF and DC.