Algebra 2 (1st Edition)

$x^2+y^2=1$
$(x – h)^2 + (y – k)^2 = r^2$ is the general equation seen for a circle where $r$ is the radius, and $(h,k)$ is the center. Matching gives $h=0, k=0, r=1$ or $(x )^2 + (y)^2 = 1^2$