F(x)=Cos^2x/3- sin^2x/3 Найти F(x)=?

Question

F(x)=Cos^2x/3- sin^2x/3
Найти F(x)=?

Answer 1

cos2x = cos^2x - sin^2x => f(x) = cos(2x/3)
Учи формулы)