:confused: 1-cot x
______

tan x - 1

What are you supposed to do? Simplify?

Rewrite as:

\frac{1-\frac{cos(x)}{sin(x)}}{\frac{sin(x)}{cos(x)}-1}

This equals:

\frac{\frac{sin(x)-cos(x)}{sin(x)}}{\frac{sin(x)-cos(x)}{cos(x)}}

=\frac{\sout{sin(x)-cos(x)}}{sin(x)}\cdot\frac{cos(x)}{\sout{sin(x)-cos(x)}}

=\frac{cos(x)}{sin(x)}=cot(x)