This is an equation in STANDARD form for a circle:
(x-h)^2 + (y-k)^2 = r^2
The values of (h, k) are the center point of the circle. When they are put into an equation, their symbols flip as in, if they are positive on a graph, they become negative in the equation and vice versa.
The value (r) is the radius and is squared in the equation. In this case, the square root of 1 is 1.
(x)^2 + (y-6)^2 = 1