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WBJEE · Maths · Trigonometric Ratios & Identities

Simplest form of \(\frac{2}{\sqrt{2+\sqrt{2+\sqrt{2+2 \cos 4 x}}}}\) is

  1. A \(\sec \frac{x}{2}\)
  2. B \(\sec x\)
  3. C \(\operatorname{cosec} x\)
  4. D 1
Verified Solution

Answer & Solution

Correct Answer

(A) \(\sec \frac{x}{2}\)

Step-by-step Solution

Detailed explanation

\[ \text { Hints : } \begin{aligned} & \frac{2}{\sqrt{2+\sqrt{2+\sqrt{2.2 \cos ^2 2 x}}}}=\frac{2}{\sqrt{2+\sqrt{2+2 \cos 2 x}}}=\frac{2}{\sqrt{2+\sqrt{2.2 \cos ^2 x}}} \\ & =\frac{2}{\sqrt{2+2 \cos x}}=\frac{2}{2 \cos \frac{x}{2}}=\sec \frac{x}{2} \end{aligned} \]