优优班--学霸训练营 > 知识点挑题
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            • 1.
              已知\(m∈R\),过原点\(O\)作圆\(x^{2}+(m+2)y^{2}-4x-8y-16m=0\)的切线,则此时的切线方程为 ______ .
            • 2.
              已知圆\(C\):\(x^{2}+y^{2}-4x-6y+12=0\)的圆心在点\(C\),点\(A(3,5)\),求:
              \((1)\)过点\(A\)的圆的切线方程;
              \((2)O\)点是坐标原点,连接\(OA\),\(OC\),求\(\triangle AOC\)的面积\(S\).
            • 3.
              直线\(l\)经过点\(P(-3,4)\)且与圆\(x^{2}+y^{2}=25\)相切,则直线\(l\)的方程是\((\)  \()\)
              A.\(y-4=- \dfrac {4}{3}(x+3)\)
              B.\(y-4= \dfrac {3}{4}(x+3)\)
              C.\(y+4=- \dfrac {4}{3}(x-3)\)
              D.\(y+4= \dfrac {3}{4}(x-3)\)
            • 4.
              如图,圆\(C\)分别与\(x\)轴正半轴,\(y\)轴正半轴相切于点\(A\),\(B\),过劣弧\( \overparen {AB}\)上一点\(T\)作圆\(C\)的切线,分别交\(x\)轴正半轴,\(y\)轴正半轴于点\(M\),\(N\),若点\(Q(2,1)\)是切线上一点,则\(\triangle MON\)周长的最小值为\((\)  \()\)
              A.\(10\)
              B.\(8\)
              C.\(4 \sqrt {5}\)
              D.\(12\)
            • 5.
              若直线\(x+y+m=0\)与圆\(x^{2}+y^{2}=m\)相切,则\(m\)的值是\((\)  \()\)
              A.\(0\)或\(2\)
              B.\(2\)
              C.\( \sqrt {2}\)
              D.\( \sqrt {2}\)或\(2\)
            • 6.
              已知直线\(5x+12y+a=0\)与圆\(x^{2}+y^{2}-2x=0\)相切,则\(a\)的值为 ______ .
            • 7.
              已知\(⊙C\):\(x^{2}+y^{2}=1\),对\(A(0,-2)\),\(B(a,2)\),从点\(A\)观察点\(B\),要使视线不被\(⊙C\)挡住,则实数\(a\)的取值范围是\((\)  \()\)
              A.\((-∞,-2)∪(2,+∞)\)
              B.\((-∞,- \dfrac {4 \sqrt {3}}{3})∪( \dfrac {4 \sqrt {3}}{3},+∞)\)
              C.\((-∞,- \dfrac {2 \sqrt {3}}{3})∪( \dfrac {2 \sqrt {3}}{3},+∞)\)
              D.\((- \dfrac {4 \sqrt {3}}{3}, \dfrac {4 \sqrt {3}}{3})\)
            • 8.
              已知点\(P\)是直线\(x+y-b=0\)上的动点,由点\(P\)向圆\(O\):\(x^{2}+y^{2}=1\)引切线,切点分别为\(M\),\(N\),且\(∠MPN=90^{\circ}\),若满足以上条件的点\(P\)有且只有一个,则\(b=(\)  \()\)
              A.\(2\)
              B.\(±2\)
              C.\( \sqrt {2}\)
              D.\(± \sqrt {2}\)
            • 9.
              已知\(p\)为直线\(x+y-2=0\)上的点,过点\(p\)作圆\(O\):\(x^{2}+y^{2}=1\)的切线,切点为\(M\),\(N\),若\(∠MPN=90^{\circ}\),则这样的点\(p\)有\((\)  \()\)
              A.\(0\)个
              B.\(1\)个
              C.\(2\)个
              D.无数个
            • 10. 已知点\(P\left( x,y \right)\)是直线\(kx+y+4=0\left( k > 0 \right)\)上的一动点,\(PA,PB\)是圆\(C:{{x}^{2}}+{{y}^{2}}-2y=0\)的两条切线\((C\)为圆心\()\),\(A,B\)是切点,若四边形\(PACB\)的面积的最小值是\(2\),则\(k\)的值为\((\)     \()\)
              A.\(3\)
              B.\(\dfrac{\sqrt{21}}{2}\)
              C.\(2\sqrt{2}\)
              D.\(2\)
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