Question

Find the intervals in which the function f given by

is (i) increasing (ii) decreasing

Answer 1

Now,

cos x = 0 or cos x = 4

But, cos x ≠ 4

∴cos x = 0

divides (0, 2π) into three disjoint intervals i.e.,

In intervals,

Thus, f(x) is increasing for

In the interval

Thus, f(x) is decreasing for.