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            • 1.

              若直线\(l\)的方向向量为\(a=(1,-1,2)\),平面\(α\)的法向量为\(u=(-2, 2,-4)\),则(    )

              A.\(l/\!/α\)                                              
              B.\(l⊥α\)
              C.\(l⊂α\)                                              
              D.\(l\)与\(α\)斜交
            • 2. 若平面 \(α\)\(β\)的法向量分别为 \(a\)\(=(-1,2,4)\), \(b\)\(=( \)\(x\),\(-1\),\(-2)\),并且 \(α\)\(⊥\) \(β\),则 \(x\)的值为(    )
              A.\(10\)                 
              B.\(-10\)
              C.\( \dfrac{1}{2}\)                                 
              D.\(- \dfrac{1}{2}\)
            • 3. 如图所示,在空间直角坐标系中\(BC=2\),原点\(O\)是\(BC\)的中点,点\(A\)的坐标是\(( \dfrac { \sqrt {3}}{2}, \dfrac {1}{2},0)\),点\(D\)在平面\(yOz\)上,且\(∠BDC=90^{\circ}\),\(∠DCB=30^{\circ}\),则向量\( \overrightarrow{AD}\)的坐标为\((\)  \()\)
              A.\((- \dfrac { \sqrt {3}}{2},- \dfrac {1}{2}, \dfrac { \sqrt {3}}{2})\)
              B.\((- \dfrac { \sqrt {3}}{2},-1, \dfrac { \sqrt {3}}{2})\)
              C.\((- \dfrac {1}{2},- \dfrac { \sqrt {3}}{2}, \dfrac { \sqrt {3}}{2})\)
              D.\(( \dfrac { \sqrt {3}}{2},1, \dfrac { \sqrt {3}}{2})\)
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