Answer
$a.\displaystyle \qquad-\frac{\sqrt{2}}{2} \\$
$b. \qquad 2 \\$
$c. \qquad -\sqrt{3}$
Work Step by Step
$ a.\displaystyle \qquad \sin(-\frac{\pi}{4})=\qquad$... even/odd properties,
$=-\displaystyle \sin(\frac{\pi}{4})=\qquad$...table p.410 ...
$=-\displaystyle \frac{\sqrt{2}}{2}$
$ b. \displaystyle \qquad \sec(-\frac{\pi}{3})=\qquad$... even/odd properties,
$=\displaystyle \sec(\frac{\pi}{3})\qquad$...table p.410...
$=2$
$ c. \displaystyle \qquad \cot(-\frac{\pi}{6})=\qquad$... even/odd properties,
$=-\displaystyle \cot(\frac{\pi}{6})=\qquad$...table p.410...
$=-\sqrt{3}$
