1. The problem statement, all variables and given/known data I've got two questions 1.Find the intervals on which f increases and and the intervals on which f decreases. f(x)= x-cosx, 0≤x≤2∏ 2. Why is f(x) = -2sin2x - 2sinx = -2sinx (2cosx + 1) How can you factor 2cosx from the function on the left side? 2. Relevant equations 3. The attempt at a solution 1.I get f '(x) = 1 + sinx, 0≤x≤2∏ The answer says that it increases on [0,2∏] but I don't get it.