Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be:
f (x) = sin x – cos x, 0 < x < 2π
f (x) = sin x – cos x, 0 < x < 2π
f’(x) = cosx + sinx
Now, f’(x) = 0
⇒ cosx + sinx = 0
⇒ cosx = -sinx
⇒ tanx = -1
’(x) = -sinx + cosx
Then, by second derivative test,
is point of local maxima and the local maximum value of f at is
And,
is point of local minima and the local minimum value of f at is