BA=OA-OB
OD=OB+(1/3)OB
设BE=tBA,
OE=mOD=mOB+(m/3)OA
OE=OB+BE=OB+t(OA-OB)=(1-t)OB+tOA
∴m=1-t,
m/3=t.即m=3t
∴ 3t=1-t
∴ t=1/4
∴ BE=1/4BA
BA=OA-OB
OD=OB+(1/3)OB
设BE=tBA,
OE=mOD=mOB+(m/3)OA
OE=OB+BE=OB+t(OA-OB)=(1-t)OB+tOA
∴m=1-t,
m/3=t.即m=3t
∴ 3t=1-t
∴ t=1/4
∴ BE=1/4BA