△abc的三条中线ad,be,cf交于o,求证ao/od=bo/oe=co/of=2/1证明：设s△obd=m,s△obf=n,s△oce=p则s△obd=s△ocd=m,s△oce=s△oae=p,s△obf=s△oaf=ns△oab=2m,2m n=s△abc=2n m2m p=2p mm=n=p所以s△aob=2s△obd所以a...