AB上D点,AD:AB=1:3,BC上E点,BE:BC=1:4,CA上F点,CF:CA=1:5,S△DEF=19,求S△ABC?

问题描述:

AB上D点,AD:AB=1:3,BC上E点,BE:BC=1:4,CA上F点,CF:CA=1:5,S△DEF=19,求S△ABC?

45.6