Let $f(x)= \log_e (\sin x), x ∈ (0,π)$, then which of the following statements is/are TRUE? (A) f(x) is increasing on (0, π/2) Choose the correct answer from the options given below: |
(C) and (D) only (A) and (B) only (A) only (B) only |
(A) and (B) only |
The correct answer is Option (2) → (A) and (B) only $f(x)=\log_e(\sin x),\;x\in(0,\pi)$ $f'(x)=\frac{d}{dx}\log(\sin x)=\frac{\cos x}{\sin x}=\cot x$ $\cot x>0\text{ on }(0,\frac{\pi}{2})\Rightarrow f \text{ increasing on }(0,\frac{\pi}{2})$ $\cot x<0\text{ on }(\frac{\pi}{2},\pi)\Rightarrow f \text{ decreasing on }(\frac{\pi}{2},\pi)$ Correct Option: (A), (B) |