# Math Help - Angle Theta

1. ## Angle Theta

As angle θ increases from π radians to 2pi radians, the cosine of θ
(1) increases throughout the interval
(2) decreases throughout the interval
(3) increases, then decreases
(4) decreases, then increases

Please, explain your answer not just select one form the choices.

2. Look at this cosine graph:

What happens when theta changes from $\pi$ to $2\pi$?

3. ## it gets...

Originally Posted by Air
Look at this cosine graph:

What happens when theta changes from $\pi$ to $2\pi$?
Theta increases then increases???

4. Here is a graph of $y = \cos{x}$ for the interval $[-2\pi, 2\pi]$. http://upload.wikimedia.org/wikipedi...px-Cos.svg.png

Between $\pi$ and $2\pi$ it can be seen that $y = cos{x}$ is always increasing (except at the exact points of $\pi$ and $2\pi$, which are stationary points)

5. Originally Posted by magentarita
Theta increases then increases???
Yes, that is correct. The only option which matches that is option (1).

6. ## Thanks

Thank you both for your great help.