优优班--学霸训练营 > 知识点挑题
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            • 1. 如图,四面体\(ABCD\)中,点\(E\)是\(CD\)的中点,记\( \overrightarrow{AB}= \overrightarrow{a}\),\( \overrightarrow{AC}= \overrightarrow{b}\),\( \overrightarrow{AD}= \overrightarrow{c}\),则\( \overrightarrow{BE}=(\)  \()\)
              A.\( \overrightarrow{a}- \dfrac {1}{2} \overrightarrow{b}+ \dfrac {1}{2} \overrightarrow{c}\)
              B.\(- \overrightarrow{a}+ \dfrac {1}{2} \overrightarrow{b}+ \dfrac {1}{2} \overrightarrow{c}\)
              C.\( \dfrac {1}{2} \overrightarrow{a}- \overrightarrow{b}+ \dfrac {1}{2} \overrightarrow{c}\)
              D.\(- \dfrac {1}{2} \overrightarrow{a}+ \overrightarrow{b}+ \dfrac {1}{2} \overrightarrow{c}\)
            • 2. 在四面体\(O-ABC\)中,\( \overset{→}{OA} =\) \(a\),\( \overset{→}{OB} =\) \(b\),\( \overset{→}{OC} =\) \(c\),\(D\)为\(BC\)的中点,\(E\)为\(AD\)的中点,则\( \overset{→}{OE} \)可表示为\((\)用 \(a\)\(b\)\(c\)表示\().\)                                  (    )
              A.\( \dfrac{1}{2} \) \(a\)\(+ \dfrac{1}{4} \) \(b\)\(+ \dfrac{1}{4} \) \(c\)
              B.\( \dfrac{1}{2} \) \(a\)\(+ \dfrac{1}{3} \) \(b\)\(- \dfrac{1}{2} \) \(c\)
              C.\( \dfrac{1}{3} \) \(a\)\(+ \dfrac{1}{4} \) \(b\)\(+ \dfrac{1}{4} \) \(c\)
              D.\( \dfrac{1}{3} \) \(a\)\(- \dfrac{1}{4} \) \(b\)\(+ \dfrac{1}{4} \) \(c\)
            • 3.

              在四棱锥\(P-ABCD\)中,\(ABCD\)为平行四边形,\(AC\)与\(BD\)交于\(O\),\(G\)为\(BD\)上一点,\(BG=2GD\),\(\overrightarrow{PA}=a\),\(\overrightarrow{PB}=b\),\(\overrightarrow{PC}=c\),试用基底\(\{a,b,c\}\)表示向量\(\overrightarrow{PG}\).

            • 4.

              \((1)\)已知点\(A(3,5,-7)\),\(B(-2,4,3)\),则点\(A\)关于\(x\)轴的对称点的坐标为________,点\(P\left( \dfrac{3}{2},\dfrac{5}{2},z \right)\)到线段\(AB\)的中点的距离为\(3\),则\(z=\)________.

              \((2)\)已知直线\(l_{1}\):\(x+my+1=0\)和\(l_{2}\):\((m-3)x-2y+13-7m=0.\)若\(l_{1}⊥l_{2}\),则\(m=\)________;若\(l_{1}/\!/l_{2}\),则\(l_{1}\)与\(l_{2}\)之间的距离\(d=\)________.

              \((3)\)在\(Rt\triangle AOB\)中,\(|OA|=4\),\(|OB|=3\),\(∠AOB=90^{\circ}\),点\(P\)是\(\triangle AOB\)内切圆上任一点,则内切圆的半径为________,点\(P\)到顶点\(A\)、\(O\)、\(B\)的距离的平方和的最大值为________.

              \((4)\)已知实数\(x\)和\(y\)满足方程\(y=\sqrt{3-{{x}^{2}}}\),则\(m=\dfrac{y+1}{x+3}\)的最大值为________;直线\(y=x+b\)与方程\(y=\sqrt{3-{{x}^{2}}}\)表示的曲线有两个公共点,则\(b\)的取值范围为________.

              \((5)\)已知圆\(O\):\(x^{2}+y^{2}=r^{2}(r > 0)\)与圆\(C\):\((x-2)^{2}+y^{2}=r^{2}\)的一个公共点\(P\),过\(P\)作与\(x\)轴平行的直线,分别交两圆与\(A\),\(B\)两点\((\)不同于\(P\)点\()\),且\(OA⊥OB\),则\(r=\)________.

              \((6)\)由曲线\(x^{2}+y^{2}=|x|+|y|\)围成的图形的面积为________.

              \((7)\)如图所示,已知平面\(α⊥\)平面\(β\),\(A\)、\(B\)是平面\(α\)与平面\(β\)的交线上的两个定点,\(DA\subset \beta \),\(CB\subset \beta \),且\(DA⊥α\),\(CB⊥α\),\(AD=4\),\(BC=8\),\(AB=6\),在平面\(α\)上有一个动点\(p\),使得\(∠APD=∠BPC\),则\(\triangle PAB\)的面积的最大值为________.


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