Give the equation of the circle centered at the origin and passing through the point (-9,0)

Answer 1

The radius is 9

x² + y² = 81

Answer 2

(x - h)² + (y - k)² = r²

h = 0, k = 0 (since centered at the origin)

The given point (-9,0) is 9 units from the origin, so the radius must be 9.

r = 9

x² + y² = 9²