x² + y²- 6x = 0(1)
x² - 6x + 9+ y² = 9
(x-3)²+y² =9
圆心C1(3,0)
x² + y² = 4 (2)
圆心C2(0, 0)
C1,C2在轴上,显然所求圆的圆心C(, 0)也在轴上
(2)-(1): 6x = 4, x= 2/3
y =±4√2/3
A(2/3, 4√2/3), B(2/3, -4√2/3)
CM = CA
CM² = CA²
(a - 2)² + 4 = (a-2/3)²+ 32/9
a =3/2
CM²= 17/4
r=√17/2
圆C的方程: (x- 3/2)²+ y²= 17/4