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在平面內有DABC和點O,若,則點O是DABC的(    )

A.重心B.垂心C.內心D.外心

B  

解析試題分析:∵;
=0,∴OB⊥AC,
同理可得OA⊥BC,∴點O是△ABC的三條高的交點,故選B。
考點:平面向量的數量積,向量垂直的條件。
點評:簡單題,兩向量垂直,它們的數量積為0.

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