1 .
的直径
,
为
上一点,
.延长
到点
,使
,连
交半圆于点
,过点
作
的垂线交
的延长线于
,则
的长度为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54275b7e571660d0a9e0370fbfe5050b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/241832fba1fb0325dd221d06fee3eaa0.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7d3240779195eb2b2e6e96137d94d02f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/63a253c7fdf589ee3dece13d5b5b5732.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8455657dde27aabe6adb7b188e031c11.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/20a541b81584a032f571159ea152c85a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/73465a1f9aa03481295bf6bd3c6903ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/35d58f9019097bd05037aefd5c322916.png)
A.![]() | B.![]() | C.![]() | D.![]() |
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2 . 如图,
与
的半径相等,交于X、Y两点.
内接于
,且其垂心H在
上,点Z使得四边形CXZY为平行四边形.证明:AB、XY、HZ三线共点.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0385df6c7f8ee7ab503b6ed35933695b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cd73875650e1538c4c61d5e16d3db29.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0385df6c7f8ee7ab503b6ed35933695b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cd73875650e1538c4c61d5e16d3db29.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/6/813bd828-c5e5-4c19-964d-3efac35ecc18.png?resizew=205)
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3 . 在
中,∠A、∠B、∠C的对边分别为a、b、c,且a=5,b=4,
.
则
的面积为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b5bd164214133b539743af0f6455aeef.png)
则
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
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4 . 如图,设L、M、N分别为
的∠BAC、∠ CBA、∠ ACB内的点,且∠BAL=∠ ACL,∠ LBA=∠ LAC,∠ CBM=∠ BAM,∠ MCB=∠ MBA,∠ ACN=∠ CBN,∠ NAC=∠ NCB.
![](https://img.xkw.com/dksih/QBM/2018/12/27/2105804516392960/2108043933114368/STEM/78ee293eaac54d828e243495e7f1e745.png?resizew=265)
证明:(1) AL、BM、CN三线交于一点P;
(2)L、M、N、P四点共圆.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://img.xkw.com/dksih/QBM/2018/12/27/2105804516392960/2108043933114368/STEM/78ee293eaac54d828e243495e7f1e745.png?resizew=265)
证明:(1) AL、BM、CN三线交于一点P;
(2)L、M、N、P四点共圆.
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5 . 在
中,证明:
,当且仅当
为正三角形时,上式等号成立.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dbd70f824a256802a1eb0c884c3a567e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
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6 . 如图,圆内接四边形ABCD的对角线AC与BD交于点N,AC的中点为M.若
,证明:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a9350af1078056c2c436f6fc4806c22.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f4ab41c53ebfd2aa1ce792778b7ed7d1.png)
![](https://img.xkw.com/dksih/QBM/2018/12/27/2105804284502016/2107812426637312/STEM/8284fd968f5c4bfaae4ed5efe3dc9ca5.png?resizew=246)
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7 . 在平面直角坐标系中,已知O为原点,点
,
,动点C在圆
上运动,则
的最大值为_________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0929421a6188c3122442866b0b85a5e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c0adc439eabb8acf3806ac8af85f0410.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8f46bd6985253f993dc2d1c12b801dc2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6cb4e379da961ee064ddf4a742edd915.png)
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8 . 如图,在
中,AB>AC,H为
的垂心,M为边BC的中点,点S在边BC上且满足∠BHM=∠CHS,点A在直线HS上的投影为P.证明:
的外接圆与
的外接圆相切.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5eddf5fcf0eff9ea16094af9260bc00d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/12/31/315ba2bf-c383-4e5e-9e33-77dd4dba7f43.png?resizew=214)
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9 . 记
.则
的最小值为__________ .
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/45eb7efe3f3f8ce08ad5375949247562.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/62d7b7f86c808602eab44cc37fbcc520.png)
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10 . 如图,已知△ABC内切圆
分别与边AB、BC、AC切于点F、D、Q,直线AD、CF分别与
交于另一点H、K,证明:
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a9353177e057491904812d73b4957589.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a9353177e057491904812d73b4957589.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/525c63b1c4eaf11255205026c5ecf799.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2023/1/5/958a4ba5-ca24-4d1b-b91d-a1954cf5a18d.png?resizew=179)
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