Answer:
Center: (0, 1); radius: 10
Step-by-step explanation:
Your x^2+y^2- 2y - 99 = 0 is centered at (0, k):
(x - 0)^2 + y^2 - 2y - 99 = 0
and you must "complete the square" of y^2- 2y
to determine the value of k:
(x - 0)^2 + y^2 - 2y + 1 - 1 - 99 = 0, or
(x - 0)^2 + (y - 1)^2 = 100 = 10^2
The center is at (h, k) : (0, -1) and the radius is 10.
The equation in final form is
x^2 + (y - 1)^2 = 10^2
The radius is 10. That is, since r^2 = 100, r must be 10.
