Mark (√) against the correct answer in the following:
is decreasing in
Given:
f(x) = sin x – cos x
f’(x) = cos x + sin x
Multiply and divide by √2.
For f(x) to be decreasing .f’(x)<0
(∵ sin θ <0 for π <θ <2π )
∴ f(x) decreases in the interval.