优优班--学霸训练营 > 知识点挑题
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            • 1.
              已知向量\( \overrightarrow{a}=(\sin x,\cos x)\),\( \overrightarrow{b}=(\sin x+\cos x,\sin x-\cos x)(x∈R)\),若\( \overrightarrow{a}⊥ \overrightarrow{b}\),则\(x\)的取值集合为\((\)  \()\)
              A.\(\{x|x= \dfrac {kπ}{2}+ \dfrac {π}{8},k∈Z\}\)
              B.\(\{x|x=kπ+ \dfrac {π}{8},k∈Z\}\)
              C.\(\{x|x= \dfrac {kπ}{2}+ \dfrac {π}{4},k∈Z\}\)
              D.\(\{x|x=kπ+ \dfrac {π}{4},k∈Z\}\)
            • 2.
              向量\( \overrightarrow{a}=( \sqrt {3},\;1)\),\( \overrightarrow{b}=( \sqrt {3},\;-1)\),\( \overrightarrow{a}\)与\( \overrightarrow{b}\)夹角的大小为 ______ .
            • 3.
              已知向量\( \overrightarrow{a}=(2,3)\),\( \overrightarrow{b}=(-1,2)\),若\(m \overrightarrow{a}+4 \overrightarrow{b}\)与\( \overrightarrow{a}-2 \overrightarrow{b}\)共线,则\(m\)的值为\((\)  \()\)
              A.\( \dfrac {1}{2}\)
              B.\(2\)
              C.\(- \dfrac {1}{2}\)
              D.\(-2\)
            • 4.
              已知向量\( \overrightarrow{a}=(1,2)\),\( \overrightarrow{b}=(x,-1)\),若\( \overrightarrow{a}/\!/( \overrightarrow{a}- \overrightarrow{b})\),则\( \overrightarrow{a}⋅ \overrightarrow{b}=\) ______ .
            • 5.
              已知\( \overrightarrow{a}=(3,4)\),\( \overrightarrow{b}=(2,k)\).
              \((1)\)若\(( \overrightarrow{a}+2 \overrightarrow{b})/\!/( \overrightarrow{a}- \overrightarrow{b})\),求\(k\)的值.
              \((2)\)若\(( \overrightarrow{a}+ \overrightarrow{b})⊥( \overrightarrow{a}- \overrightarrow{b})\),求\(k\)的值.
            • 6.
              在\(\triangle ABC\)中,角\(A\),\(B\),\(C\)的对边分别为\(a\),\(b\),\(c\),且满足\((2a-c)\cos B=b\cos C\);
              \((1)\)求角\(B\)的大小;
              \((2)\)设\( \overrightarrow{m}=(\sin A,\cos 2A)\),\( \overrightarrow{n}=(4k,1)(k > 1)\),且\( \overrightarrow{m}⋅ \overrightarrow{n}\)的最大值是\(5\),求\(k\)的值.
            • 7.
              已知向量\( \overrightarrow{a}=(-1,-3)\),\( \overrightarrow{b}=(2,t)\),且\( \overrightarrow{a}/\!/ \overrightarrow{b}\),则\( \overrightarrow{a}- \overrightarrow{b}=\) ______ .
            • 8.
              若向量\( \overrightarrow{BA}=(1,2)\),\( \overrightarrow{CA}=(4,5)\),则\( \overrightarrow{BC}=(\)  \()\)
              A.\((5,7)\)
              B.\((-3,-3)\)
              C.\((3,3)\)
              D.\((-5,-7)\)
            • 9.
              设向量\( \overrightarrow{a}=(1,-3)\),\( \overrightarrow{b}=(-2,4)\),若表示向量\(4 \overrightarrow{a}\),\(3 \overrightarrow{b}-2 \overrightarrow{a}\),\( \overrightarrow{c}\)的有向线段首尾相接能构成三角形,则向量\( \overrightarrow{c}\)为\((\)  \()\)
              A.\((1,-1)\)
              B.\((-1,1)\)
              C.\((-4,6)\)
              D.\((4,-6)\)
            • 10.
              设\( \overrightarrow{OA}=(3,1)\),\( \overrightarrow{OB}=(-1,2)\),\( \overrightarrow{OC}⊥ \overrightarrow{OB}\),\( \overrightarrow{BC}/\!/ \overrightarrow{OA}\),试求满足\( \overrightarrow{OD}+ \overrightarrow{OA}= \overrightarrow{OC}\)的\( \overrightarrow{OD}\)的坐标\((O\)为坐标原点\()\).
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