答案
解:①当点C在点B右侧上时,此时AC=AB+BC=u4cm,∵M是线段AC的中点,则AM=
AC=7cm;
②当点C在点B的左侧时,AC=AB-BC=6cm,∵M是线段AC的中点,则AM=
AC=acm.
综上所述,线段AM的长为7cm或acm.
解:①当点C在点B右侧上时,此时AC=AB+BC=u4cm,∵M是线段AC的中点,则AM=
AC=7cm;
②当点C在点B的左侧时,AC=AB-BC=6cm,∵M是线段AC的中点,则AM=
AC=acm.
综上所述,线段AM的长为7cm或acm.