解答题-证明题 较难0.4 引用4 组卷171
如图,AB是⊙O的直径,弦CD⊥AB于G ,射线DO与直线CE相交于E,直线DB与CE相交于H,且∠BDC=∠BCH.
(1)求证:直线CE是⊙O的切线.
(2)如图1,若OG=BG,BH=1,直接写出⊙O的半径:_______.
(3)如图2,在(2)的条件下,将射线DO绕D逆时针旋转,得射线DM,DM与AB交于M,与⊙O及切线CF分别相交于点N,F,当GM=GD时,求切线CF的长.
![](https://img.xkw.com/dksih/QBM/2019/5/15/2204373260042240/2209697402404864/STEM/a09b36b32db241c8b994c0c8181b0870.png?resizew=364)
(1)求证:直线CE是⊙O的切线.
(2)如图1,若OG=BG,BH=1,直接写出⊙O的半径:_______.
(3)如图2,在(2)的条件下,将射线DO绕D逆时针旋转,得射线DM,DM与AB交于M,与⊙O及切线CF分别相交于点N,F,当GM=GD时,求切线CF的长.
![](https://img.xkw.com/dksih/QBM/2019/5/15/2204373260042240/2209697402404864/STEM/a09b36b32db241c8b994c0c8181b0870.png?resizew=364)
2019·广东深圳·一模
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