cách giải ở trong sách
- ngutoanso1 likes this
Posted by hkh172 on 20-09-2015 - 21:29
Posted by hkh172 on 19-09-2015 - 22:02
a. $\underset{MA}{\rightarrow}+\underset{MB}{\rightarrow}=2\underset{MI}{\rightarrow} \Rightarrow \underset{IA}{\rightarrow}+\underset{IB}{\rightarrow}=\underset{0}{\rightarrow}\Rightarrow \underset{IA}{\rightarrow}=-\underset{IB}{\rightarrow}\Rightarrow$ I là trung điểm AM.
b. $ \underset{MA}{\rightarrow}+\underset{MB}{\rightarrow}+\underset{MC}{\rightarrow}=3\underset{MG}{\rightarrow}\Rightarrow \underset{GA}{\rightarrow}+\underset{GB}{\rightarrow}+\underset{GC}{\rightarrow}=\underset{0}{\rightarrow}\Rightarrow $ G là trọng tâm tam giác ABC.
Community Forum Software by IP.Board
Licensed to: Diễn đàn Toán học