[tex]1) \: tan( - \pi) = tan(\pi) = \frac{sin(\pi)}{cos(\pi)} = \frac{ \: \: \: 0}{ - 1} = 0[/tex]
[tex]2) \: tan (\frac{ { - 7\pi} }{4} ) = tan \: ( \frac{ \pi}{4} + \frac{ - 8\pi}{ \: \: 4} ) \\ = tan \: ( \frac{\pi}{4} - 2\pi) = tan \: ( \frac{\pi}{4} ) = 1[/tex]
Hope this helps :)
