如圖1，線段AC＝6cm，線段BC＝15cm，點M是AC的中點，在CB上取一點N，使得CN：NB＝1：2，求M...
來源：國語幫 1.33W
問題詳情：
如圖1，線段AC＝6cm，線段BC＝15cm，點M是AC的中點，在CB上取一點N，使得CN：NB＝1：2，求MN的長．
【回答】
解：∵M是AC的中點，AC＝6，
∴MC＝
AC＝6×
＝3，·············································································· 1分
又因為CN∶NB＝1∶2，BC＝15，
∴CN＝15×
＝5，·························································································· 3分
∴MN＝MC＋CN＝3＋5＝8，
∴MN的長為8 cm·························································································· 4分
知識點：直*、*線、線段
題型：解答題
