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若圆x2+y2-2x-4y=0的圆心到直线x-y+a=0的距离为,则a的值为( ...
若圆x
2+y
2-2x-4y=0的圆心到直线x-y+a=0的距离为
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123721212975621/SYS201310251237212129756003_ST/0.png)
,则a的值为( )
A.-2或2
B.
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123721212975621/SYS201310251237212129756003_ST/1.png)
或
![manfen5.com 满分网](http://img.manfen5.com/res/GZSX/web/STSource/20131025123721212975621/SYS201310251237212129756003_ST/2.png)
C.2或0
D.-2或0
考点分析:
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