己知圆c的一般方程式为x+y-4x-2y+f=0,且该圆通过点(0,1),求圆c的圆心,半径
圆通过点(0,-1),0+1+0+2+f=0,f=-3
x^2+y^2-4x-2y-3=0,
(x-2)^2+(y-1)^2=8
圆心(2,1),半径r=2√2,
圆心到直线y=2x-8的距离d
d=|2*2-1-8|/√5=5/√5=√5
绛旓細鍦嗛氳繃鐐(0,-1),0+1+0+2+f=0,f=-3 x^2+y^2-4x-2y-3=0,(x-2)^2+(y-1)^2=8 鍦嗗績(2,1),鍗婂緞r=2鈭2,鍦嗗績鍒扮洿绾縴=2x-8鐨勮窛绂籨 d=|2*2-1-8|/鈭5=5/鈭5=鈭5
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