# Thread: Simple fundamental identity problem

1. ## Simple fundamental identity problem

I just have a pretty simple question, if someone could show me how it's done that would be great!

Complete the fundamental identity:
cos(w-z) using Angle Difference which is cos( θ- φ) = cosθcos φ + sinθsin φ

2. Originally Posted by alexcross
I just have a pretty simple question, if someone could show me how it's done that would be great!

Complete the fundamental identity:
cos(w-z) using Angle Difference which is cos( θ- φ) = cosθcos φ + sinθsin φ
(cosw)(cosz)+(sinw)(sinz)

3. So is this as far as I can go in the problem?

4. Yes, unless you have more special info about the variables in question.