Answer
Circle in the xz-plane of radius $1$ centered at $(0,0,4)$
Work Step by Step
We put
$$ x=\sin t,\quad y=0, \quad z=4+\cos t $$
hence we get
$$ x^2+(z-4)^2= \sin^2t+\cos^2t=1.$$
Which is a circle in the xz-plane of raduis $1 $ centered at $(0,0,4)$.
