Question

How do you simplify using the sum and difference formula `cos75`?

Answer 1

`cos75=(sqrt3 -1)/(2sqrt2)`

Explanation:

`cos75 = cos (30+45) = cos30*cos45 - sin30*sin45 =(sqrt3/2)(1/sqrt2) - 1/2*(1/sqrt2) = (sqrt3 -1)/(2sqrt2)`[Ans]