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AP EAMCET · Maths · Application of Derivatives

The number of all the values of \(x\) for which the function \(f(x)=\sin x+\frac{1-\tan ^2 x}{1+\tan ^2 x}\) attains its maximum value on \([0,2 \pi]\) is

  1. A 4
  2. B 1
  3. C 2
  4. D infinite
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Answer & Solution

Correct Answer

(C) 2

Step-by-step Solution

Detailed explanation

\begin{aligned} & \text { } f(x)=\sin x+\frac{1-\tan ^2 x}{1+\tan ^2 x} \Rightarrow f(x)=\sin x+\cos 2 x \\ & f^{\prime}(x)=\cos x-2 \sin 2 x=0 \Rightarrow \cos x=2 \sin 2 x \\ & \Rightarrow 1=2 \sin x \Rightarrow \sin x=\sin \frac{\pi}{6} \Rightarrow x=n \pi+(-1)^n…