Math.atan()

A função Math.atan() retorna a arco tangente (em radianos) de um número, onde

$$\mathtt{\operatorname{Math.atan}(x)} = \arctan(x) = \text{ the unique } ; y \in \left[-\frac{\pi}{2}; \frac{\pi}{2}\right] , \text{such that} ; \tan(y) = x$$

Math.atan(x)

Math.atan(1); // 0.7853981633974483
Math.atan(0); // 0
Math.atan(-0); // -0

Math.atan(Infinity); //  1.5707963267948966
Math.atan(-Infinity); // -1.5707963267948966

// The angle that the line [(0,0);(x,y)] forms with the x-axis in a Cartesian coordinate system
Math.atan(y / x);