# Math Help - Basic Cosine

1. ## Basic Cosine

Im having a brain fade here, and I know this is basic algebra, but cant remember how to do it. I need to solve for cos(theta)

1-cos(theta)=1+cos(theta)

Thanks for your help

2. Originally Posted by BCHurricane89
Im having a brain fade here, and I know this is basic algebra, but cant remember how to do it. I need to solve for cos(theta)

1-cos(theta)=1+cos(theta)

Thanks for your help
Add $cos(\theta)$ to both sides and then add $-1$ to both sides:

$2cos(\theta) = 0$

$\theta = \frac{\pi}{2} \pm k\pi$ where k is an integer

3. doh! that kinda what I thought, except the book had cos(theta)=0, but we have 2cos(theta)=0