Answer:
center: (0,0)
radius: 4 units
Step-by-step explanation:
the circle goes through points (0,4), (0,-4), (4,0), and -4,0).
if you notice, all four points are 4 away from the origin, (0,0). this means that there center is (0,0).
if you start at one of the points and go to the origin, it will be 4 units. that will be your radius
