2. using the unit circle, find the value of cos (11π/6). √3/2 -√3/3 -1/2 -√3

Explanation:

Step1: Rewrite the angle

We know that $\frac{11\pi}{6}=2\pi-\frac{\pi}{6}$.

Step2: Use cosine property

Since $\cos(2\pi - \alpha)=\cos\alpha$, then $\cos(\frac{11\pi}{6})=\cos(2\pi-\frac{\pi}{6})=\cos\frac{\pi}{6}$.

Step3: Recall unit - circle value

On the unit circle, $\cos\frac{\pi}{6}=\frac{\sqrt{3}}{2}$.

Answer:

$\frac{\sqrt{3}}{2}$