Determine the interval, where f(x)=sin x - cos x, 0<x<2pie is strictly increasing or decreasing?
For f (x) to be increasing f'(x) > 0
∴ f (x) increases in the interval
For f (x) to be decreasing, f'(x) < 0
∴ f (x)decreases in the interval
∴ f (x) increases in the interval and decreases in the interval