G là trọng tâm ΔABC
\(\overrightarrow{\rm GA}+\overrightarrow{\rm GB}+\overrightarrow{\rm GC}=\overrightarrow{\rm 0}\)
G là trọng tâm ΔAEF
\(\overrightarrow{\rm GA}+\overrightarrow{\rm GE}+\overrightarrow{\rm GC}=\overrightarrow{\rm 0}\)
\(\overrightarrow{\rm GA}+\overrightarrow{\rm GE}+\overrightarrow{\rm GC}=\overrightarrow{\rm GA}+\overrightarrow{\rm GE}+\overrightarrow{\rm GF}\)
\(\overrightarrow{\rm GB}+\overrightarrow{\rm GC}=\overrightarrow{\rm GE}+\overrightarrow{\rm GF}\)
\(\overrightarrow{\rm GE}+\overrightarrow{\rm EB}+\overrightarrow{\rm GC}=\overrightarrow{\rm GE}+\overrightarrow{\rm GC}+\overrightarrow{\rm GF}\)
\(\overrightarrow{\rm EB}=\overrightarrow{\rm CF}\)
\(\overrightarrow{\rm EB}=\overrightarrow{\rm FC}\)
G là trọng tâm ΔABC
\(\overrightarrow{\rm GA}+\overrightarrow{\rm GB}+\overrightarrow{\rm GC}=\overrightarrow{\rm 0}\)
G là trọng tâm ΔAEF
\(\overrightarrow{\rm GA}+\overrightarrow{\rm GE}+\overrightarrow{\rm GC}=\overrightarrow{\rm 0}\)
\(\overrightarrow{\rm GA}+\overrightarrow{\rm GE}+\overrightarrow{\rm GC}=\overrightarrow{\rm GA}+\overrightarrow{\rm GE}+\overrightarrow{\rm GF}\)
\(\overrightarrow{\rm GB}+\overrightarrow{\rm GC}=\overrightarrow{\rm GE}+\overrightarrow{\rm GF}\)
\(\overrightarrow{\rm GE}+\overrightarrow{\rm EB}+\overrightarrow{\rm GC}=\overrightarrow{\rm GE}+\overrightarrow{\rm GC}+\overrightarrow{\rm GF}\)
\(\overrightarrow{\rm EB}=\overrightarrow{\rm CF}\)
\(\overrightarrow{\rm EB}=\overrightarrow{\rm FC}\)