已知直线x+ay﹣1=0是圆C：x2+y2﹣4x﹣2y+1=0的对称轴，过点A（﹣4，a）作圆C的一条切线，切点为B，则|AB|=_刷题宝

题干

已知直线x+ay﹣1=0是圆C：x²+y²﹣4x﹣2y+1=0的对称轴，过点A（﹣4，a）作圆C的一条切线，切点为B，则|AB|=（　　）

A：2

B：6

C：4 $\sqrt{2}$

D：2 $\sqrt{10}$

上一题下一题 0.0难度选择题更新时间:2019-04-04 04:46:25

答案(点此获取答案解析）

B

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