## Calculus 8th Edition

A circle with radius $\sqrt5$, centered at $(0,0)$.
$r^2=5$ Since $r^2=x^2+y^2$, we get: $x^2+y^2=5$ This is the circle formula ($x^2+y^2=r^2$) and describes a circle with radius $\sqrt5$, centered at $(0,0)$.