Answer:
[tex]\frac{\pi}{6}[/tex] radians
[tex]cos(\frac{7\pi}{6})=-\frac{\sqrt{3}}{2}[/tex]
Step-by-step explanation:
A reference angle is an acute angle between the terminal arm/terminal side and the x-axis. In this case, the reference angle is [tex]\frac{7\pi}{6}-\pi=\frac{\pi}{6}[/tex].
As for [tex]cos(\frac{7\pi}{6})[/tex], we can identify the value of it using the unit circle as attached below. Recall that points on the unit circle are defined as [tex](cos(\theta),sin(\theta))[/tex], so [tex]cos(\frac{7\pi}{6})=-\frac{\sqrt{3}}{2}[/tex].
