# Thread: Solving Trigonometric inequality with unit circle??

1. ## Solving Trigonometric inequality with unit circle??

The practice problem i am working on is solve cos(x) >= sqrt(3)/2. I need to use the unit circle, I think, since a practice problem in my book uses it with the same type of problem. Could anyone work through this problem for me? I have no idea where to start!

2. ## Re: Solving Trigonometric inequality with unit circle??

Originally Posted by glambeth
The practice problem i am working on is solve cos(x) >= sqrt(3)/2. I need to use the unit circle, I think, since a practice problem in my book uses it with the same type of problem. Could anyone work through this problem for me? I have no idea where to start!
look at the unit circle ...

$\displaystyle \cos{x} = \frac{\sqrt{3}}{2}$ at $\displaystyle x = \frac{\pi}{6}$ and $\displaystyle x = -\frac{\pi}{6}$

so $\displaystyle \cos{x} \ge \frac{\sqrt{3}}{2}$ for values of x in the interval $\displaystyle -\frac{\pi}{6} \le x \le \frac{\pi}{6}$