From square ABCD: AD=AB, ∠ DAF = ∠ BAE = 90,

∫AF = 1/2AB, e is the midpoint of AD,

∴AF=AE

In △ABE and △ADF,

AD=AB

BAE =∠DAF

AE=AF

∴△abe≌△adf(sas)；

(2)

In the figure, the position of △ABE rotates 90 around point A to become △ADF.

(3)

Solution: ∫ Quadrilateral ABCD is a square,

∴AD=AB,∠BAD=90，

∫E is the midpoint of AD, AF= 1/2AB,

∴AE=AF，

∴ △ADF can be obtained by rotating △ABE 90 counterclockwise around point A,

∴BE=DF,BE⊥DF.