# ArcTan2

The function $\operatorname{atan2}(y,x)$ (from "2-argument arctangent") is defined as the angle in the Euclidean plane, given in radians, between the positive x-axis and the ray to the point $(x,y)$. $\operatorname{atan2}(y,x)$ returns a single value $\theta$ such that $-\pi < \theta \le \pi$ and, for some $r > 0$, x&=r\cos \theta \\ y&=r\sin \theta

r &= \sqrt{x^2 + y^2} = \\ \theta &= \operatorname{atan2}(y,x) =