Question

[Hoangtrang Trương]

Gọi G là trọng tâm tam giác ABC. Đặt \(\overrightarrow{a}=\overrightarrow{GA},\overrightarrow{b}=\overrightarrow{GB.}\)Hãy biểu thị mỗi vecto \(\overrightarrow{AB},\overrightarrow{GC},\overrightarrow{BC},\overrightarrow{CA}\) qua các vecto \(\overrightarrow{a},\overrightarrow{b}\)

Answer 1

[Nguyễn Lê Phước Thịnh]

\(\overrightarrow{AB}=\overrightarrow{AG}+\overrightarrow{GB}=\overrightarrow{b}-\overrightarrow{a}\)

\(\overrightarrow{GC}=0-\overrightarrow{GA}-\overrightarrow{GB}=-\overrightarrow{a}-\overrightarrow{b}\)

\(\overrightarrow{BC}=\overrightarrow{BG}+\overrightarrow{GC}=-\overrightarrow{b}-\overrightarrow{a}-\overrightarrow{b}=-\overrightarrow{a}-2\overrightarrow{b}\)

\(\overrightarrow{CA}=\overrightarrow{CG}+\overrightarrow{GA}=\overrightarrow{a}+\overrightarrow{b}+\overrightarrow{a}=2\overrightarrow{a}+\overrightarrow{b}\)