将线段AB延长到C,使BC=1/3AB,反向延长AC到D点使AD=1/2AC,则CD=多少AB?

将线段AB延长到C,使BC=1/3AB,反向延长AC到D点使AD=1/2AC,则CD=多少AB?
将线段AB延长到C,使BC=1/3AB,反向延长AC到D点使AD=1/2AC,则CD=多少AB?

将线段AB延长到C,使BC=1/3AB,反向延长AC到D点使AD=1/2AC,则CD=多少AB?
BC=1/3AB
AC=AB+BC=4/3AB
AD=1/2AC=（1/2）×（4/3AB）=2/3AB
CD=AD+AC
=2/3AB+2/3AB
=（2/3+4/3）AB
=2AB