How i solve a non linear equation with 4 unknowns??

Hello everyone!

I'm trying to find the center(x0,y0,z0) and radius (r) of the circle/circumference. I I have 4 points with coordinates x, y and z and i need solve this system:

(x0-x1)^2+(y0-y1)^2+(z0-z1)^2=r^2

(x0-x2)^2+(y0-y2)^2+(z0-z2)^2=r^2

(x0-x3)^2+(y0-y3)^2+(z0-z3)^2=r^2

(x0-x4)^2+(y0-y3)^2+(z0-z4)^2=r^2

I need to get x0,y0,z0 and r.

Does anyone have any idea how to do this in Matlab?

Thanks