Question

已知圆：x^+y^+4x+10y+4=0 (1)点A(1,-2)在圆内,过点A作直线l,并被圆所截得的弦被点A平分,求此

Answer 1

圆的方程是(x+2)^2+(y+5)^2=25设 圆心是O(-2,-5),半径是5

1 当直线被圆所截,且被A平分,A与圆心的连线垂直于该直线 k(AO)=1 则k=-1

直线是y=-x-1

2 k(BO)=4/3 k=-3/4 y=-3/4x-1/4

3 设该直线过（1,0）则方程是y=kx-k与x^+y^+4x+10y+4=0联合求解