Chapter 7 - Trigonometry and Periodic Functions - 7.6 The Tangent Function - Exercises and Problems for Section 7.6 - Exercises and Problems - Page 303: 18

A flip of $\tan \theta$ around the $y$-axis.

$\tan(-\theta)$ is the same as $f(-\theta)$ for $f(\theta)=\tan \theta$. Since $f(-\theta)$ is a reflection of $f(x)$ about the $y$-axis, this function is a flip of $\tan x$ about the $y$-axis.