1 . 如图所示,PA与圆O相切于点A,不过圆心O的割线PCB与直径AE相交于D点.已知∠BPA=30°,AD=2,PC=1,则圆O的半径等于________ .
![](https://img.xkw.com/dksih/QBM/2017/8/14/1758200027602944/1817081830203392/STEM/91b436abd3534b12b4bbcc4893490293.png?resizew=87)
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11-12高三上·山东聊城·阶段练习
2 . 如图,
是内接于
,
,直线
切
于点
,弦
,
与
相交于点
.
(I) 求证:
≌
;
(Ⅱ)若
,求
.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0faed94a64b2dcfc6801b4fca0f16675.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/047dc9795efa99b6fb9fdf9778085dab.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3d97cdc586744d208b6f69c9813af977.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3947b65d110d74021faf8156b2f4d709.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2a30f3a8b673cc28bd90c50cf1a35281.png)
(I) 求证:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cc3814287dbb60d478bffc5366f9928b.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d9f8f01137e92c0f2e63467036ae9cce.png)
(Ⅱ)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/19592a5eaacb7752f792d43652b43db8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/68a83fdd2ba72a2dba0b6b10bb3e06b9.png)
![](https://img.xkw.com/dksih/QBM/2011/12/25/1570632677564416/1570632682971136/STEM/8d453e2dd3474110b2e9f240122c8547.png?resizew=141)
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