试题分析:(Ⅰ)
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夹角为
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,若
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则
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;若
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则
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5分
(Ⅱ)
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. 10分
点评:向量平行则方向相同或相反,夹角为
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,求向量模时利用
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将求模转化为向量运算
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平面向量
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与
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的夹角为
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,
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=(2,0),
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="1" 则
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=( )
A. | B. | C.4 | D.12 |
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的夹角为
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,|
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+
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