将三角形纸片△ABC按如图所示的方式折叠,使点B落在边AC上,记为点B′,折痕为EF.已知AB=AC=6,BC=8,若以

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  • ∵△ABC沿EF折叠B和B′重合,

    ∴BF=B′F,

    设BF=x,则CF=8-x,

    ∵当△B′FC ∽ △ABC,

    B ′ F

    AB =

    CF

    BC ,

    ∵AB=6,BC=8,

    x

    6 =

    8-x

    8 ,

    解得:x=

    24

    7 ,

    即:BF=

    24

    7 ,

    当△FB′C ∽ △ABC,

    FB′

    AB =

    FC

    AC ,

    x

    6 =

    8-x

    6 ,

    解得:x=4,

    当△ABC ∽ △CBF′时,同法可求BF=4,

    故BF=4或

    24

    7 ,

    故选:D.