1. f(x)= x+2cosx
2. f(x)= x+2sinx
3. f(x)= e^x (sinx)
Regarding problem number 1, I know that the derivative is 1-2sinx, then when I set it equal to zero I get sinx=1/2. Therefor it would be pi/6, but the answer key says that the answer is 2npi + pi/6, 2npi + 5pi/6. I need some clarification on how to reach that conclusion.
On problem 2, I get the answer cosx= -1/2. The answer key says that the final answer is (2n +1)pi +/- pi/3. Again I am quite sure how to reach that conclusion or final answer.
Same problem on 3. tanx= -1: What would my next step be to solve the problem.
Any feedback or help would be appreciated. These problems have been bugging me all day.