已知向量
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,
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,
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,則
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與
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夾角的最小值和最大值依次是 ( )
設(shè)
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與
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夾角為
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,∵
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,
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,∴點A在以點C(2,2)為圓心半徑為
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的圓上,由題意點B在x軸上,可知直線OA為圓的切線時
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與
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夾角取得最小值和最大值,設(shè)切線為y=kx,則由
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得k=
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,故當(dāng)k=
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時
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與
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夾角為
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最小,此時
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,
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=
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,當(dāng)k=
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時
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與
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夾角為
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最大,此時
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,
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=
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,故選C
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( )
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
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在面積為
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的
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中,
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分別是
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,
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在直線
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已知三點
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,
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,
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
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
是曲線
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上的動點,曲線
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在點
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處的切線為
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,點
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的坐標(biāo)是
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,
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與
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,
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,
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如圖所示,在
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中,

,

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y軸上,且

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(Ⅱ)過點
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作互相垂直的兩條直線
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,
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與點
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A、
B,
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與點
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C、
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
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已知兩點

,
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,若直線
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上存在點
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滿足
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,則實數(shù)

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在△ABC中,已知
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