Answer
$\int_0^\frac{\pi}{4} (tan x ) dx$
Work Step by Step
Interpreting Limits of sums as Integrals
-$\lim\limits_{||p|| \to 0}$ $\Sigma^n_{k=1} (tan c_k) Δx_k $
where P is a partition of $[0,\frac{\pi}{4}]$
--$\int_0^\frac{\pi}{4} (tan x ) dx$
