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科目:高中數(shù)學(xué)
來源:不詳
題型:解答題
(本小題滿分10分)已知向量
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,
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,
(I)求與
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平行的單位向量
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;
(II)設(shè)
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,若存在
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使得
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成立,求
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的取值范圍。
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科目:高中數(shù)學(xué)
來源:不詳
題型:單選題
若向量
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,
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、
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的夾角的余弦值為
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,則
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=( )
A.2 | B.-2 | C.-2或 | D.2或- |
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科目:高中數(shù)學(xué)
來源:不詳
題型:單選題
設(shè)向量
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和
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的長度分別為4和3,夾角為60°,則|
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+
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|的值為( )
A.37 | B. | C.13 | D. |
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科目:高中數(shù)學(xué)
來源:不詳
題型:單選題
向量
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,
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的
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夾角為
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,則稱
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◎
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為
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,
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的積,定義
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◎
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,若
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,
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,
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, 則
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◎
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等于
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