# arc-tangent

The inverse of the tangent function, usually abbreviated arctan. It is defined such that for all real numbers, $$\arctan(x)=a$$ if and only if $$\tan(a)=x$$. The principal arctangent takes its values in the interval $$\left[-\frac{\pi}{2},\frac{\pi}{2}\right]$$.

Arctangent may also be abbreviated by atan or tan-1.