[tex] \cot( \binom{\pi}{4} - \alpha ) [/tex]

[tex] \frac{\pi}{4} = 45[/tex]

[tex] \cot( \frac{\pi}{4} - \alpha ) = \frac{1 + \tan( \frac{\pi}{4} ) \times \tan( \alpha ) }{ \tan( \frac{\pi}{4} ) - \tan( \alpha ) } [/tex]

[tex] \cot( \frac{\pi}{4} - \alpha ) = \frac{1 + \tan( \alpha ) }{1 - \tan( \alpha ) } [/tex]