The standard form of a circle is:
(x-h)^2+(y-k)^2=r^2, where (h,k) is the (x,y) coordinate of the center of the circle and r is its radius. In this case:
(h,k) is (1,5) and it has a radius of √4 which is 2
So the center is the point (1,5) and it has a radius of 2.
