Finding monotone increasing interval of function y = cos (x / 2 - π / 3), X ∈ [- 2 π, 2 π]

Finding monotone increasing interval of function y = cos (x / 2 - π / 3), X ∈ [- 2 π, 2 π]


Monotone increasing interval of y = - cos (x / 2 - π / 3)
That is to say, we can find the decreasing interval of y = cos (x / 2 - π / 3)
2kπ