Gaokao Math Practice Question
已知圆 $C: x^{2}+y^{2}=4$, 直线 $l: y=k x+m$, 当 $k$ 变化时, $l$ 截得圆 $C$ 弦长的最小值为 2 , 则 $m=(\quad)$
- A.$\pm 2$
- B.$\pm \sqrt{2}$
- C.$\pm \sqrt{3}$
- D.$\pm \sqrt{5}$
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