x2 + (y + 5)2 = 25 ---> x2 + y2 + 10y + 25 = 25 ---> x2 + y2 + 10y = 0
x2 + y2 = r2 ---> r2 + 10y = 0
y = r·sin(theta) ---> r2 + 10·r·sin(theta) = 0 ---> r2 = - 10·r·sin(theta)
Either r = 0 [the pole] or r = -10·sin(theta)
Since the pole is covered by the equation: r = -10·sin(theta)