共50条信息
在空间四边形\(OABC\)中,\(\overrightarrow{OA}=a\),\(\overrightarrow{OB}=b\),\(\overrightarrow{OC}=c\),点\(M\)在\(OA\)上,且\(OM=2MA\),\(N\)为\(BC\)的中点,给出以下向量\(;\)其中与\(\overrightarrow{MN}\)平行的向量是________\((\)只填相应序号即可\()\).
\(①3a-4b+3c\);\(②-4a+3b+3c\);\(③3a+3b-4c\);\(④\dfrac{4}{3}a-b-c\).
已知向量\(\overrightarrow{a}=(2,-1,4)\),\(\overrightarrow{b}=(-4,2,x)\),\(\overrightarrow{c}=(1,x,2)\),若\((\overrightarrow{a}+\overrightarrow{b})\bot \overrightarrow{c}\),则\(x\)等于________.
已知向量\(a=(0,-1,1)\),\(b=(4,1,0)\),\(|λa+b|= \sqrt{29}\)且\(λ > 0\),则实数\(λ=\)________.
在空间平移\(\triangle ABC\)到\(\triangle A_{1}B_{1}C_{1}(\)使\(\triangle A_{1}B_{1}C_{1}\)与\(\triangle ABC\)不共面\()\),连接对应顶点,设\(\overset{→}{A{A}_{1}}= \overset{→}{a} \),\(\overset{→}{AB}= \overset{→}{b} \),\(\overset{→}{AC}= \overset{→}{c} \),\(M\)是\(BC_{1}\)的中点,\(N\)是\(B_{1}C_{1}\)的中点,用基底\(\left\{ \overset{→}{a}, \overset{→}{b}, \overset{→}{c}\right\} \)表示向量\(\overrightarrow{AM}+\overrightarrow{AN}\)的结果是__________.
已知\(\overrightarrow{OA}=(1,2,4),\overrightarrow{OB}=(2,1,1),\overrightarrow{OP}=(1,1,2)\),点\(Q\)在直线\(OP\)上运动,则当\(\overrightarrow{QA}\cdot \overrightarrow{QB}\)取得最小值时,点\(Q\)的坐标为___________。
已知\(S\)是\(\triangle ABC\)所在平面外一点,\(D\)是\(SC\)的中点,若\(\overrightarrow{BD}=x\overrightarrow{AB}+y\overrightarrow{AC}+z\overrightarrow{AS}\),则\(x+y+z=\)__________.
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