# Homework Help: Summing cosines of sines and cosines

1. Jun 11, 2012

### matlabber

1. The problem statement, all variables and given/known data

$$\sum_{t=0}^{n-1}cos2 \pi ft(x_{t}- \mu-Acos2 \pi ft-Bsin2 \pi ft)$$

2. Relevant equations

3. The attempt at a solution
I know to set = 0
I just am not knowing what to do with the cos after the sum...how do I take this sum?

2. Jun 12, 2012

### tiny-tim

hi matlabber!

i suspect they mean $\sum_{t=0}^{n-1}(cos2 \pi ft)(x_{t}- \mu-Acos2 \pi ft-Bsin2 \pi ft)$