((x0-x1)^2+(y0-y1)^2)^0.5 < R0+R1
(ie. if the distance between the two centres is less than the sum of the two radus)
For real circles. DOnt know how relevent to your program
(ie. if the distance between the two centres is less than the sum of the two radus)
For real circles. DOnt know how relevent to your program