Given
[tex]\cos (\frac{5\pi}{6})[/tex]
To evaluate.
Now,
It is given that,
[tex]\cos (\frac{5\pi}{6})[/tex]
Then,
[tex]\begin{gathered} \cos (\frac{5\pi}{6})=\cos (\frac{6\pi-\pi}{6}) \\ =\cos (\pi-\frac{\pi}{6}) \end{gathered}[/tex]
Since
[tex]\cos (\pi-\theta)=-\cos \theta[/tex]
Then,
[tex]\begin{gathered} \cos (\frac{5\pi}{6})=\cos (\pi-\frac{\pi}{6}) \\ =-\cos \frac{\pi}{6} \\ =-\frac{\sqrt[]{3}}{2} \\ =-0.866025403 \end{gathered}[/tex]
Hence, the value is -0.866025403.
