Question

f(x) = sin x is increasing in

A. (π/2, π)

B. (π, 3π/2)

C. (0, π)

D. (-π/2, π/2)

Answer 1

Answer is : D. (-π/2, π/2)

Given: f(x) is sin x

∴ f’(x) = cos x

⇒ f’(x) = cos x

= 0

⇒ for x ∈ (-π/2, π/2)

f’(x) is increasing

∴ f(x) is increasing in (-π/2, π/2).