Question 229503
all points (in a plane) that are equidistant from a given point, form a circle


in this case, the center of the circle is (0, -1); and the radius is 1


for a circle centered at (h, k) with radius r, the general equation is (x-h)^2 + (y-k)^2 = r^2


in this case ___ (x-0)^2 + (y - -1)^2 = 1^2 ___ x^2 + y^2 + 2y + 1 = 1