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CUET · MATHS · PYQ PAPER 2025

If \(f(x) = sin\) \(x - cos\) \(x\), \(x \in[0,2 \pi]\) then
(A) f(x) is increasing in \(\left(0, \frac{3 \pi}{4}\right)\)
(B) f(x) is decreasing in \(\left(0, \frac{3 \pi}{4}\right)\)
(C) f(x) is decreasing in \(\left(\frac{3 \pi}{4}, \frac{7 \pi}{4}\right)\)
(D) f(x) is decreasing in \(\left(\frac{7 \pi}{4}, 2 \pi\right)\)
Choose the correct answer from the options given below:

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

Answer & Solution

Correct Answer

(C) (A) and (C) only

Step-by-step Solution

Detailed explanation

\(f(x) = \sin x - \cos x\) \(f'(x) = \cos x + \sin x\) \(f'(x) = 0 \implies \cos x + \sin x = 0 \implies \tan x = -1\) \(x = \frac{3\pi}{4}, \frac{7\pi}{4}\) For \(x \in \left(0, \frac{3\pi}{4}\right)\), e.g., \(x = \frac{\pi}{2}\):…
From CUET
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