Answer
$\sin{(-\frac{5\pi}{6})}= -0.5$
Work Step by Step
The angle $-\dfrac{5\pi}{6}$ is in Quadrant III.
Its reference angle is $\dfrac{\pi}{6}$.
Note that $\dfrac{\pi}{6}$ is a special angle and that $\sin{(\frac{\pi}{6})}=0.5$.
The trigonometric function values of an angle and its reference angle are either the same or differ only in signs.
Since $-\dfrac{5\pi}{6}$ terminates in Quadrant III, then its sine is negative.
Therefore,
$\sin{(-\frac{5\pi}{6})}= -0.5$.
