[tex]\bf \cfrac{1-cot(x)}{tan(x)-1}\qquad
\begin{cases}
cot(\theta)=\cfrac{cos(\theta)}{sin(\theta)}
\\\\ tan(\theta)=\cfrac{sin(\theta)}{cos(\theta)}
\end{cases}\qquad thus
\\\\\\
\cfrac{1-\frac{cos(x)}{sin(x)}}{\frac{sin(x)}{cos(x)}-1}\implies
\cfrac{\frac{sin(x)-cos(x)}{sin(x)}}{\frac{sin(x)-cos(x)}{cos(x)}}\\\\
-----------------------------\\\\
recall\implies \cfrac{\frac{a}{b}}{\frac{c}{{{ d}}}}\implies \cfrac{a}{b}\cdot \cfrac{{{ d}}}{c}\qquad thus\\\\
-----------------------------[/tex]
[tex]\bf \cfrac{\frac{sin(x)-cos(x)}{sin(x)}}{\frac{sin(x)-cos(x)}{cos(x)}}\implies \cfrac{sin(x)-cos(x)}{sin(x)}\cdot \cfrac{cos(x)}{sin(x)-cos(x)}\implies \boxed{?}[/tex]
