圆x^2 + y^2 + 6x +5=0,即 (x + 3)^2+ y^2 = 2^2圆x^2 + y^2 - 6x -91=0,即 (x - 3)^2+ y^2 = 10^2设动圆的圆心为O(x,y),据题意,利用动圆心与两个已知圆心的距离关系：√[(x + 3)^2+ y^2] - 2 = 10 - √[(x - 3)^2+ ...