∴DF=？ .
CE = again? BC,
∴DF=CE and df∑ce,
∴ Quadrilateral CEDF is a parallelogram;
(2) Analysis
As shown in the figure, DH⊥BE at point H.
Are you online? In ABCD, ∫∠b = 60,
∴∠DCE=60。
AB = 4，
∴CD=AB=4，
∴CH=2,DH=2？ .
Are you online? In CEDF, CE=DF=? AD=3, then eh = 1.
∴ in Rt△DHE, do you know DE= according to Pythagorean theorem? =? .