## Thomas' Calculus 13th Edition

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