Question

Express as a single trigonmetric function, then evaluate.

cos32cos28-sin32sin28
I think the single trig function is: cos(a-b) therefore cos(32-28) but that gives me cos4.
How do I evaluate this?

Answer 1

I believe you can only evaluate it with a caculator

Answer 2

Nevermind, I made a mistake. Cosacosb-sinacosb = cos(a+b) for anyone who wanted to know. Thanks

Answer 3

cos(60) is from the unit circle, that would be easy to evaluate