W
wally12


cho hinh binh hanh` ABCD.Dung [TEX]\vec{AM}=\vec{BA}[/TEX] , [TEX]\vec{MN}=\vec{DA}[/TEX], [TEX]\vec{NP}=\vec{DC}[/TEX] , [TEX]\vec{PQ}= \vec{BC}[/TEX].chung minh [TEX]\vec{AQ}=\vec{0}[/TEX]
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