Question

Question #efb55

Answer 1

This can be simplified using the sum and difference formula for cosine:

`cos(A - B) = cosAcosB + sinAsinB`

In this formula, `A = 80˚` and `B = 20˚`, thus the given expression is equivalent to

`cos(60˚)`

Which in turn is equivalent to `1/2`. I don't know what the rest of the question is asking.

Sorry I couldn't be of more help.