# increasing and decreasing functions

#### sydewayzlocc

For the function f(x)=sin(x)+cos(x) on the interval (0, 2pi) I am supposed to find where f(x) is increasing or decreasing. I took the derivative of the function and came up with f'(x) = cos(x)-sin(x) which i set equal to zero, what do I need to do next?

#### Prove It

MHF Helper
For the function f(x)=sin(x)+cos(x) on the interval (0, 2pi) I am supposed to find where f(x) is increasing or decreasing. I took the derivative of the function, what do I need to do next?
It's increasing when $$\displaystyle f'(x) > 0$$ and decreasing when $$\displaystyle f'(x) < 0$$.

#### sydewayzlocc

It's increasing when $$\displaystyle f'(x) > 0$$ and decreasing when $$\displaystyle f'(x) < 0$$.
Don't I need to find the critical numbers and make a table

#### HallsofIvy

MHF Helper
Do that and then use what Prove It said.