Chapter 10 - Conics, Parametric Equations, and Polar Coordinates - 10.4 Exercises - Page 723: 87

$${x^2} + {y^2} = {6^2}$$

$$\eqalign{ & r = 6 \cr & {\text{Convert to rectangular form using }}{r^2} = {x^2} + {y^2} \cr & \sqrt {{x^2} + {y^2}} = 6 \cr & {\left( {\sqrt {{x^2} + {y^2}} } \right)^2} = {\left( 6 \right)^2} \cr & {x^2} + {y^2} = {6^2} \cr & {\text{The equation represents a circle of radius 6 centered at the origin}} \cr & {\text{Graph}} \cr} $$