如图,已知三角形ABC,延长BC到D,使CD=BC,取AB中点F,连接FD交AC于点E.求AE比AC的值_数学解答

如图,已知三角形ABC,延长BC到D,使CD=BC,取AB中点F,连接FD交AC于点E.求AE比AC的值

人气：363 ℃　时间：2019-08-16 23:44:52

解答

过点F作FG‖BC,交AC于点G.因为,FG‖BC,AF = FB = (1/2)AB ,所以,AG = GC = (1/2)AC ,FG = (1/2)BC .因为,FG‖CD,FG = (1/2)BC = (1/2)CD ,所以,GE = (1/2)EC .因为,GE∶EC = 1∶2 ,可得：GE∶GC = GE∶(GE+EC) = 1∶...