Temos dois casos:
[tex3]\begin{cases} \tg x\,-\,1\,=\,0 \\ \text{ou} \\ 4\cdot\sen ^2x\,-\,3\,=\,0\end{cases}[/tex3]
No primeiro:
[tex3]\text{tg}x\,=\,1\,\,\Longleftrightarrow\,\,x\,=\,\frac{\pi}{4}\,+\,2k\pi \,\,\,,\,\,\forall \,k\,\in\,N\,\,\Longrightarrow\,\,\boxed{a\,=\,\frac{\pi}{4}}[/tex3]...