# How do you find the average rate of change of f(x) = tan(x) from x=0 to x=pi/4?

The average rate of change of $f \left(x\right) = \tan x$ is
$\frac{f \left(\frac{\pi}{4}\right) - f \left(0\right)}{\frac{\pi}{4} - 0} = \frac{1}{\frac{\pi}{4}} = \frac{4}{\pi}$