線段AB=12釐米,點M是AB中點,點C在MB上且MC:CB=2:1,求線段AC的長?

線段AB=12釐米,點M是AB中點,點C在MB上且MC:CB=2:1,求線段AC的長?

AM=MB=AB/2=12/2=6,
MC=2/3MB=2/3*6=4,
AC=AM+MC=6+4=10.