1,⊿AFC≌⊿CGB,
2,CF=BG,
BG/BE=BC/(BC+CE)=2/3''''''''''''''''''''①
⊿BCE∽⊿ADE,AE/DE=BE/CE=√5,∴AE=CE=3/2·√5,即BE=15/2.'''''''''''''''''''''''②
2,CF=BG,
BG/BE=BC/(BC+CE)=2/3''''''''''''''''''''①
⊿BCE∽⊿ADE,AE/DE=BE/CE=√5,∴AE=CE=3/2·√5,即BE=15/2.'''''''''''''''''''''''②