Question

[quangduy]

Cho hình bình hành ABCD tâm O, M là điểm bất kỳ. CMR:

a) \(\overrightarrow{MC}+\overrightarrow{MA}=\overrightarrow{MB}+\overrightarrow{MD}\)

b) \(\overrightarrow{MC}-\overrightarrow{MD}=\overrightarrow{AB}\)

c) \(\overrightarrow{BD}-\overrightarrow{BA}=\overrightarrow{OC}-\overrightarrow{OB}\)

d) \(\overrightarrow{BC}-\overrightarrow{BD}+\overrightarrow{BA}=\overrightarrow{0}\)

Answer 1

[Bình Minh]

b) \(VP=\overrightarrow{MC}-\overrightarrow{MD}=\overrightarrow{DC}=\overrightarrow{AB}=VP\left(đpcm\right)\)

c) \(\overrightarrow{BD}-\overrightarrow{BA}=\overrightarrow{OC}-\overrightarrow{OB}\\ \Leftrightarrow\overrightarrow{AD}=\overrightarrow{BC}\left(đúng\right)\\ \)

d) \(\overrightarrow{BC}-\overrightarrow{BD}+\overrightarrow{BA}=\overrightarrow{0}\\ \Rightarrow\overrightarrow{DC}+\overrightarrow{BA}=\overrightarrow{0}\\ \Leftrightarrow\overrightarrow{0}=\overrightarrow{0}\left(đúng\right)\)