persamaan lingkaran yg melalui titik (0,-1),(2,3),(1,6)

Rumus : x^2 + y^2= r^2
a. (0,-1)
x^2+(-y)^2 = r^2
0 +1 = r ^2
√1 = r
persamaannya :
x^2 + y^2 = r^2
x^2 + y^2 = √1^2
x^2 + y^2 = 1

b. (2,3)
langsung aja ya
2^2+3^2 = r^2
4+9 = r^2
13 = r^2
√13 = r
persamaannya
x^2 + y^2 = 13


c.(1,6)
1^2 + 6^2 = r^2
√37 = r
persamaannya
x^2+ y^2 = 37