优优班--学霸训练营 > 知识点挑题
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            • 1.
              已知直线\(l_{1}\):\(x⋅\sin α+y-1=0\),直线\(l_{2}\):\(x-3y⋅\cos α+1=0\),若\(l_{1}⊥l_{2}\),则\(\sin 2α=(\)  \()\)
              A.\( \dfrac {2}{3}\)
              B.\(± \dfrac {3}{5}\)
              C.\(- \dfrac {3}{5}\)
              D.\( \dfrac {3}{5}\)
            • 2.
              已知\(b > 0\),直线\((b^{2}+1)x+ay+2=0\)与直线\(x-b^{2}y-1=0\)互相垂直,则\(ab\)的最小值等于\((\)  \()\)
              A.\(1\)
              B.\(2\)
              C.\(2 \sqrt {2}\)
              D.\(2 \sqrt {3}\)
            • 3.
              已知倾斜角为\(θ\)的直线\(l\)与直线\(x+2y-3=0\)垂直,则\(\sin 2θ\)的值为\((\)  \()\)
              A.\( \dfrac {3}{5}\)
              B.\( \dfrac {4}{5}\)
              C.\( \dfrac {1}{5}\)
              D.\(- \dfrac {1}{5}\)
            • 4.

              设三条直线\(3x+2y+6=0,2x-3{m}^{2}y+18=0和2mx-3y+12=0 \)围成直角三角形,则\(m\)的取值是          

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