Answer
-1
Work Step by Step
cot(-t) = -cot t
cot(-$\frac{5\pi}{4}$) = -cot $\frac{5\pi}{4}$
-cot($\frac{\pi}{4}$ + $\pi$) = -cot$\frac{\pi}{4}$
-cot t=$\frac{1}{-tan t}$
-cot$\frac{\pi}{4}$ = $\frac{1}{-tan \frac{\pi}{4}}$
-cot$\frac{\pi}{4}$ =$\frac{1}{-1}$ = -1
