Exercise 6

Does the equation $\sin^{2}(x)/\cos^{2}(x)=\tan^{2}(x)$ show that this set of functions $\{\hskip 1.00006pt\sin^{2}(x),\cos^{2}(x),\tan^{2}(x)\hskip 1.00006pt\}$ is a linearly dependent subset of the set of all real-valued functions with domain the interval $(-\pi/2..\pi/2)$ of real numbers between $-\pi/2$ and $\pi/2)$?