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/8
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/8