过O做OM∥AD交AB于M
易得OM=1/2AD=2,BM=1/2AB=3
∴△BFE∽△MFO
∴BE/OM=BF/FM
BE/2=BF/(3+BF),BE=2BF/(3+BF)
∵BE+CE=AD=4
CE+BF=6
∴6-BF+2BF/(3+BF)=4
BF²-BF-6=0
BF=3
BF=-2( 舍去)
过O做OM∥AD交AB于M
易得OM=1/2AD=2,BM=1/2AB=3
∴△BFE∽△MFO
∴BE/OM=BF/FM
BE/2=BF/(3+BF),BE=2BF/(3+BF)
∵BE+CE=AD=4
CE+BF=6
∴6-BF+2BF/(3+BF)=4
BF²-BF-6=0
BF=3
BF=-2( 舍去)