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CUET · MATHS · PYQ PAPER 2025

Let \(f(x)=\log _e(\sin x), x \in(0, \pi)\), then which of the following statements is/are TRUE?
(A) \(f(x)\) is increasing on \((0, \pi / 2)\)
(B) \(f ( x )\) is decreasing on \(( \pi / 2 , \pi)\)
(C) \(f(x)\) is increasing on \((0, \pi)\)
(D) \(f(x)\) is decreasing on \((0, \pi)\)
Choose the correct answer from the options given below :

  1. A (C) and (D) only
  2. B (A) and (B) only
  3. C (A) only
  4. D (B) only
Verified Solution

Answer & Solution

Correct Answer

(B) (A) and (B) only

Step-by-step Solution

Detailed explanation

\(f'(x) = \frac{d}{dx}(\log_e(\sin x)) = \frac{1}{\sin x} \cdot \cos x = \cot x\) For \(x \in (0, \pi/2)\), \(\cot x > 0\), so \(f(x)\) is increasing on \((0, \pi/2)\). For \(x \in (\pi/2, \pi)\), \(\cot x Statements (A) and (B) are TRUE.