Q23 of 105 Page 17

Show that f(x) = sin x – cos x is an increasing function on (–π /4, π /4)?

we have,

f(x) = sin x – cos x


f'(x) = cos x + sin x





Now,








⇒ f'(x)>0


Hence, f(x) is an increasing function on (–π /4, π /4)


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