# What is meant by tan^(-1)(y/x) in a polar coordinate formula?

$\theta = {\tan}^{- 1} \left(\frac{y}{x}\right) \Leftrightarrow \tan \theta = \frac{y}{x}$.
So, it is an angle in $\left(- \frac{\pi}{2} , \frac{\pi}{2}\right)$ that makes tangent equal to $\frac{y}{x}$.