The function ${\bf r} \left( t \right)$ traces a circle. Determine the radius, center, and plane containing the circle
${\bf r} \left( t \right) = -6 {\bf i} \, +$ $\left( 9 \cos(t) \right) {\bf j} \, +$ $\left( 9 \sin(t) \right) {\bf k}$

Plane : $x =$
Circle's Center : ( , , )
Radius :