1 . 如图,已知
是
的外接圆,AB=BC,AD是BC边上的高,AE是
的直径.
![](https://img.xkw.com/dksih/QBM/2016/2/22/1572489983975424/1572489989963776/STEM/50c3e0070b13459e883842f9cf513f57.png)
(1)求证:
;
(2)过点C作
的切线交BA的延长线于点F,若AF=4,CF=6,求AC的长.
![](https://img.xkw.com/dksih/QBM/2016/2/22/1572489983975424/1572489989963776/STEM/8ab2ae51d7c84c7f98fd027a2c02eb9b.png)
![](https://img.xkw.com/dksih/QBM/2016/2/22/1572489983975424/1572489989963776/STEM/7fb14140b7684ef190294171f8650ae5.png)
![](https://img.xkw.com/dksih/QBM/2016/2/22/1572489983975424/1572489989963776/STEM/8ab2ae51d7c84c7f98fd027a2c02eb9b.png)
![](https://img.xkw.com/dksih/QBM/2016/2/22/1572489983975424/1572489989963776/STEM/50c3e0070b13459e883842f9cf513f57.png)
(1)求证:
![](https://img.xkw.com/dksih/QBM/2016/2/22/1572489983975424/1572489989963776/STEM/0bba7a92d47346738d69885b23e69e35.png)
(2)过点C作
![](https://img.xkw.com/dksih/QBM/2016/2/22/1572489983975424/1572489989963776/STEM/8ab2ae51d7c84c7f98fd027a2c02eb9b.png)
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14-15高三上·河南·期中
2 . 选修4-1:几何证明选讲如图,已知圆上的
,过C点的圆的切线与BA的延长线交于E点.
![](https://img.xkw.com/dksih/QBM/2014/11/25/1571902921383936/1571902927413248/STEM/aac9fa294d6e430da924bde6c166019c.png)
(Ⅰ)求证:∠ACE=∠BCD;
(Ⅱ)若BE=9,CD=1,求BC的长.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7de966c316db1013defc56372fcf814e.png)
![](https://img.xkw.com/dksih/QBM/2014/11/25/1571902921383936/1571902927413248/STEM/aac9fa294d6e430da924bde6c166019c.png)
(Ⅰ)求证:∠ACE=∠BCD;
(Ⅱ)若BE=9,CD=1,求BC的长.
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