求下列各圆方程：(1)过点A(-2,0),圆心在(3,-2) (2)圆心在直线2x-y-7=0上的圆C与y轴交与两点A(0,-4).B(0,-2

(1)r^2=(3+2)^2+(-2-0)^2=29
(X-3)^2+(y+2)^2=29
(2)A(0,-4).B(0,-2)r的垂直平分线:y=-3
又因为,圆心在直线2x-y-7=0上,得圆心(2,-3)
r^2=(0-2)^2+(-2+3)^2=5
(x-2)^2+(y+3)^2=5
(注:半径=圆心到圆上一点的距离)