Answer
$x^2+y^2=16 $
circle, center $(0,0)$ (pole), radius $r=4$.
See graph.
Work Step by Step
1. Use the formula $r^2=x^2+y^2$, we have $r=4 \rightarrow r^2=16 \rightarrow x^2+y^2=16 $
2. We can identify the above equation as a circle with center $(0,0)$ (pole), radius $r=4$.
3. See graph.
