The equations of four circles are (x±a)2+(y±a)2=a2. The radius of a circle touching all four circles is
The equation of four circles are (x±a)2+(y±a)2=a2 . The radius of a circle touching all the four circles is
The equation of four circles are (x+a)2+(y+a)2=a2. The radius of a circle touching all the four circles is
If the equations of four circles are (x±4)2+(y±4)2=42 then the radius of the smallest circle touching all the four circles is