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JEE Mains · Maths · STD 12 - 2. inverse trigonometric function

A possible value of \(\tan \left(\frac{1}{4} \sin ^{-1} \frac{\sqrt{63}}{8}\right)\) is :

  1. A \(\frac{1}{\sqrt{7}}\)
  2. B \(2 \sqrt{2}-1\)
  3. C \(\sqrt{7}-1\)
  4. D \(\frac{1}{2 \sqrt{2}}\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(\frac{1}{\sqrt{7}}\)

Step-by-step Solution

Detailed explanation

Let \(\frac{1}{4} \sin ^{-1} \frac{\sqrt{63}}{8}=\theta\) \(\sin 4 \theta=\frac{\sqrt{63}}{8}\) \(\cos 4 \theta=\frac{1}{8}\) \(2 \cos ^{2} 2 \theta-1=\frac{1}{8}\) \(\cos ^{2} 2 \theta=\frac{9}{16}\) \(\cos 2 \theta=\frac{3}{4}\) \(2 \cos ^{2} \theta-1=\frac{3}{4}\)…
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