Find the points of local maxima or local minima, if any, of the following functions, using the first derivative test. Also, find the local maximum or local minimum values, as the case may be:

f(x) = cos x, 0 < x < π

f(x) = cos x


Differentiate w.r.t x


f ’(x) = – sin x


for the point of local maxima and minima,


f ‘ (x) = 0


= – sin x = 0


x = 0, and π


But, these two interval lies outside the interval (0,π)


So, no local maxima and minima will exist in the interval (0, π)


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