1 若延长线断AB到C使BC=5/4AB,D为AC终点,求BD.2 若反向延长线段AB到C使BC=5/4AB,D为BC终点,求AD长.
问题描述：
1 若延长线断AB到C使BC=5/4AB,D为AC终点,求BD.2 若反向延长线段AB到C使BC=5/4AB,D为BC终点,求AD长.
答
1.如图：A.B.D.C因为BC=5/4AB,则AC=AB+BC=AB+5AB/4=9AB/4；D为AC中点,则AD=0.5*AC=0.5*9AB/4=9AB/8.则BD=AD-AB=9AB/8-AB=AB/8.2.如图：C.A.D.B因为BC=5/4AB,且D为BC中点,则BD=0.5*BC=5AB/8,则AD=AB-BD=AB-5AB/8=3AB/...