∫Rt triangle ABC, ∠ cab = 30.

∴∠ABC=60

In the equilateral triangle ADB.

∠BAD=∠ABC=60

AB=AD

AOD=∠ACB=90 degrees

∴BC≌△DAO(AAS)

∴F is the midpoint of Germany.

∴DO=AC

In an equilateral triangle

AC=EA，∠EAC=60

∴DO=AE

∠DAB=∠EAC=60

∴∠DAB+∠CAB=∠EAC+∠CAB

That is, ∠EAB=∠DAC.

Education for all = OFD

∴△EAF≌△DOF(AAS)

∴EF=DF

∴