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AP EAMCET · Maths · Differentiation

Find the value of \(k\) if \(\frac{d}{d x}\left\{\frac{2}{\sqrt{2+\sqrt{2+\sqrt{2+2 \cos (4 x)}}}}\right\}\) \(=k \sec \left(\frac{x}{2}\right) \tan \left(\frac{x}{2}\right)\)

  1. A \(\frac{1}{2}\)
  2. B 2
  3. C 1
  4. D \(\frac{1}{8}\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(\frac{1}{2}\)

Step-by-step Solution

Detailed explanation

\begin{aligned} & \text { Let } y=\frac{2}{\sqrt{2+\sqrt{2+\sqrt{2+2 \cos 4 x}}}} \\ & \because \quad 1+\cos 2 A=2 \cos ^2 A \\ & \therefore y=\frac{2}{\sqrt{2+\sqrt{2+\sqrt{2(1+\cos 4 x)}}}} \\ & =\frac{2}{\sqrt{2+\sqrt{2+\sqrt{4 \cos ^2 2 x}}}}=\frac{2}{\sqrt{2+\sqrt{2+2 \cos…