Question

cho hình bình hành ABCD tâm O. Đặt \(\overrightarrow{AO}=\overrightarrow{a},\overrightarrow{BO}=\overrightarrow{b}\). Tính \(\overrightarrow{AB};\overrightarrow{BC};\overrightarrow{CD};\overrightarrow{DA}\) theo \(\overrightarrow{a}\) và \(\overrightarrow{b}\)

Answer 1

\(\overrightarrow{AB}=\overrightarrow{AO}+\overrightarrow{OB}=\overrightarrow{a}-\overrightarrow{b}\)

\(\overrightarrow{AO}=\overrightarrow{OC}=\overrightarrow{a};\overrightarrow{BO}=\overrightarrow{OD}=\overrightarrow{b}\)

\(\overrightarrow{BC}=\overrightarrow{BO}+\overrightarrow{OC}=\overrightarrow{b}+\overrightarrow{a}\)

\(\overrightarrow{CD}=\overrightarrow{CO}+\overrightarrow{OD}=-\overrightarrow{a}+\overrightarrow{b}\)