题目内容
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5 |
分析:连结BC,设AE=x,根据垂直于弦的直径的性质,得到CE=
CD=
且CE2=AE•BE,可得x(6-x)=5,解出AE=5,再在RtACE中,利用勾股定理即可算出AC长.
1 |
2 |
5 |
解答:解:连结BC,AB、CD相交于点E,设AE=x
∵直径AB垂直于弦CD,
∴CE=
CD=
,且CE2=AE•BE,可得x(6-x)=5
解之得x=5
∵Rt△ACE中,AE=5,CE=
∴由勾股定理,得AC=
=
.
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∵直径AB垂直于弦CD,
∴CE=
1 |
2 |
5 |
解之得x=5
∵Rt△ACE中,AE=5,CE=
5 |
∴由勾股定理,得AC=
AE2+CE2 |
30 |
点评:本题给出垂直于弦的直径,求弦AC的长.着重考查了圆中垂直于弦的直径的性质、射影定理和勾股定理等知识,属于中档题.
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