Question

cho 6 điểm A,B,C,D,E,F, chứng minh rằng:

vecto AD + vecto BE + vecto CF = vecto AE + vecto BF + vecto CD

Answer 1

\(\overrightarrow{AD}+\overrightarrow{BE}+\overrightarrow{CF}=\overrightarrow{AE}+\overrightarrow{BF}+\overrightarrow{CD}\)

=>\(\overrightarrow{AD}-\overrightarrow{AE}+\overrightarrow{BE}-\overrightarrow{BF}+\overrightarrow{CF}-\overrightarrow{CD}=\overrightarrow{0}\)

=>\(\overrightarrow{ED}+\overrightarrow{FE}+\overrightarrow{DF}=\overrightarrow{0}\)

=>\(\overrightarrow{FD}+\overrightarrow{DF}=\overrightarrow{0}\)

=>\(\overrightarrow{FF}=\overrightarrow{0}\)(luôn đúng)