1. The axes touch the circle in the points P(r,0) and Q(0,r). The center of the circle must be situated in the 3rd quadrant and on the line y = x.

2. The circle has the equation

According to 1) the coordinates of the center must be equal C(-r , -r):

3. Plug in the coordinates of P, Q, C and the coordinmates of the given point:

Solve for r.

4. You'll get 2 circles which satisfy the given conditions.