∫B(-2，-2)，C(4，-2)，

∴M must be on the straight line x= 1

As can be seen from the figure, the vertical line of AC passes through (1, 0), so m (1, 0);

Let m be MD⊥BC in D and connect MB.

In Rt△MBD, MD=2, BD=3,

From Pythagorean Theorem: MB=MD2+BD2= 13,

That is, the radius of the circumscribed circle of △ABC is 13.