I assume that the equation of a circle in with the centre is:
Now plug in the values yxou know. You'll get 3 equations:
Expand the LHS of these equations. Then substract equ2 from equ1 and equ3 from equ1. You'll get 2 linear equations without any squares which will give you the values of m1 and m2. Afterwards you can calculate the value of r.
For confirmation only M(11, 2) and r = 10