As shown in the figure, △ ABC, D and E are the midpoint of BC and AC respectively. BF bisects ∠ ABC and intersects de at point F. if BC = 6, the length of DF is______ ．

∵ D and E are the middle points of BC and AC respectively, ∵ de ∥ AB, ∵ BFD = ∵ ABF, ∵ BF is the bisector, ∵ ABF = ∵ FBD, ∵ FBD = ∵ BFD, ∵ DF = dB, ∵ DB = DC, ∵ DF = 12bc = 3

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