在面積為
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的正
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中,
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分別是
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的中點,點
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在直線
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上,則
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的最小值是___________。
試題分析:∵
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是
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的中點,∴
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到
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的距離為點
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到
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的距離的
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,
∴
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,又
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,所以
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,
由向量夾角公式,有:
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,
∴
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,
由余弦定理,有:
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,
顯然,
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都是正數(shù),所以
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,
所以
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.
∴
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令
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,則:
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在
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中,顯然有
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都是正數(shù),所以
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,
所以
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的最小值是
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.
點評:要解決此類問題,需要牢固掌握多個知識點的內(nèi)容并靈活應(yīng)用,要有較強的邏輯思維能力和分析問題、解決問題的能力.
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