Answer
$ f(x)=\tan^2 x $ is contiuous on its domain.
Work Step by Step
We know that $\tan^2 x=\frac{\sin^2x}{\cos^2x}$ is defined for all $ x\in R $ such that $ x\neq \frac{(2n+1)\pi}{2}$, $ n $ is integer. Since $\sin x $ and $\cos x $ are continuous then by using the continuity laws, $ f(x)=\tan^2 x $ is continuous on its domain.
