(a) What is the distance from an arbitrary point $(x,y)$ in $\mathbb{R}^2$ to the $x$-axis?


(b) Find a fully simplified equation for the set of all points $P = (x,y)$ equidistant from the $x$-axis and the point $\left(-3,1\right)$. Plot a graph of this set of points and describe this set geometrically.
$y =$ help (formulas)