Circle

Circle with center at the origin (0,0)

x² + y² = r²
Where the center is (0,0) and the radius is r.

x² + y² = r²
center (0,0)
radius = 5

Circle with center at point (h,k)

(x-h)² + (y-k)² = r²
Where the center is (h,k) and the radius is r.

(x-4)² + (y-4)² = 25
center (4,4)
radius = 5

Distance Formula