Thread: increasing and decreasing functions

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?

Originally Posted by 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, what do I need to do next?

It's increasing when and decreasing when .

Originally Posted by Prove It

It's increasing when and decreasing when .

Don't I need to find the critical numbers and make a table

Do that and then use what Prove It said.