Question: how to find the slope of a circle?
Answer: Plug in the x and y value of the point on the circle whose slope you wish to find. For example, if you wanted to find the slope at the point (0,4) you would plug 0 in for x and 4 in for y in the equation dy/dx = -2x / (2(y-1)), resulting in (-2_0) / (2_4) = 0, so the slope at that point is zero.