What is the derivative of the function $f(x)=\log(\tan x)$?

$\sec x\tan x$ $\text {sec x cosecx }$ $\tan x$ $1/\sec x$

$\text {sec x cosecx }$

$f'(x)=(1/\tan x)\frac{d}{dx}(\tan x)=\frac{1}{tan x} sec^2 x=\text {sec x  cosecx }$