设DC＝x.⊿ADE∽⊿ACB ∴﹙3-x﹚/3＝x/2 x＝6/5
AD＝3-6/5＝9/5
△ADE,△EFB,△ACB周长之比＝9/5∶6/5∶3＝3∶2∶5
△ADE,△EFB,△ACB面积之比＝9∶4∶25赞同8| 评论