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            • 1.

              设平面\(\alpha{/\!/}\)平面\(\beta{,}A{,}C{∈}\alpha{,}B{,}D{∈}\beta\),直线\(AB\)与\(CD\)交于点\(S\),且点\(S\)位于平面\(\alpha{,}\beta\)之间,\({AS}{=}8{,}{BS}{=}6{,}{CS}{=}12\),则\({SD}{=}\) ______ .

            • 2.
              如图所示,\(AB\)为圆\(O\)的直径,\(CB\),\(CD\)为圆\(O\)的切线,\(B\),\(D\)为切点.
              \((1)\)求证:\(AD/\!/OC\);
              \((2)\)若圆\(O\)的半径为\(2\),求\(AD⋅OC\)的值.
            • 3.

              选修\(4-1\):几何证明选讲

              如图,\(∆ABC \)的角平分线\(AD \)的延长线交它的外接圆于点\(E \).


              \((\)Ⅰ\()\)证明:\( \dfrac{AB}{AE}= \dfrac{AD}{AC} \);

              \((\)Ⅱ\()\)若\(∆ABC \)的面积\(S= \dfrac{1}{2}AD·AE \),求\(∠BAC \)的大小.

            • 4.
              \((\)几何证明选做题\()\)
              如图,弦\(AB\)与\(CD\)相交于\(⊙O\)内一点\(E\),过\(E\)作\(BC\)的平行线与\(AD\)的延长线相交于点\(P.\)已知\(PD=2DA=2\),则\(PE=\) ______ .
            • 5.
              如图,\(A\),\(H\)在圆上,过点\(H\)作圆的切线\(BC\),\(AB\),\(AC\)分别交圆于点\(M\),\(N\).
              \((1)\)求证:\(HB⋅HM⋅CN=HC⋅HN⋅BM\);
              \((2)\)若\(AH\)为圆的直径,求证:\(\triangle AMN\)∽\(\triangle ACB\).
            • 6.
              如图,\(C\)点在圆\(O\)直径\(BE\)的延长线上,\(CA\)切圆\(O\)于\(A\)点,\(∠ACB\)平分线\(DC\)交\(AE\)于点\(F\),交\(AB\)于\(D\)点.
              \((\)Ⅰ\()\)求\(∠ADF\)的度数;
              \((\)Ⅱ\()\)若\(AB=AC\),求\(AC\):\(BC\).
            • 7.
              如图,\(⊙O_{1}\)和\(⊙O_{2}\)公切线\(AD\)和\(BC\)相交于点\(D\),\(A\)、\(B\)、\(C\)为切点,直线\(DO_{1}\)与\(⊙O_{1}\)与\(E\)、\(G\)两点,直线\(DO_{2}\)交\(⊙O_{2}\)与\(F\)、\(H\)两点.
              \((1)\)求证:\(\triangle DEF~\triangle DHG\);
              \((2)\)若\(⊙O_{1}\)和\(⊙O_{2}\)的半径之比为\(9\):\(16\),求\( \dfrac {DE}{DF}\)的值.
            • 8.
              如图所示,在▱\(ABCD\)中,\(E\)为\(CD\)上一点,\(DE\):\(CE=2\):\(3\),连接\(AE\),\(BE\),\(BD\),且\(AE\),\(BD\)交与点\(F\),则\(S_{\triangle DEF}\):\(S_{\triangle EBF}\):\(S_{\triangle ABF}\)等于\((\)  \()\)
              A.\(4\):\(10\):\(25\)
              B.\(4\):\(9\):\(25\)
              C.\(2\):\(3\):\(5\)
              D.\(2\):\(5\):\(25\)
            • 9.
              如图所示,\(CD\)为\(Rt\triangle ABC\)斜边\(AB\)边上的中线,\(CE⊥CD\),\(CE= \dfrac {10}{3}\),连接\(DE\)交\(BC\)于点\(F\),\(AC=4\),\(BC=3\).
              求证:\((1)\triangle ABC\)∽\(\triangle EDC\);   \((2)DF=EF\).
            • 10.
              如图,在梯形\(ABCD\)中,\(AB/\!/CD\),\(AB=4\),\(CD=2.E\),\(F\)分别为\(AD\),\(BC\)上点,且\(EF=3\),\(EF/\!/AB\),则梯形\(ABFE\)与梯形\(EFCD\)的面积比为 ______ .
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