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

For \(k \in R\), let the solutions of the equation \(\cos \left(\sin ^{-1}\left(x \cot \left(\tan ^{-1}\left(\cos \left(\sin ^{-1} x\right)\right)\right)\right)\right)=k, 0\,<\,|x|<\,\frac{1}{\sqrt{2}}\) be \(\alpha\) and \(\beta\), where the inverse trigonometric functions take only principal values. If the solutions of the equation \(x ^{2}- bx -5=0\) are \(\frac{1}{\alpha^{2}}+\frac{1}{\beta^{2}}\) and \(\frac{\alpha}{\beta}\), then \(\frac{b}{k^{2}}\) is equal to\(......\)

  1. A \(11\)
  2. B \(13\)
  3. C \(12\)
  4. D \(14\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(12\)

Step-by-step Solution

Detailed explanation

\(\cos \left(\sin ^{-1} x\right)=\cos \left(\cos ^{-1} \sqrt{1-x^{2}}\right)=\sqrt{1-x^{2}}\) \(\cot \left(\tan ^{-1} \sqrt{1-x^{2}}\right)=\cot ^{-1} \cot ^{-1}\left(\sqrt{\left.\frac{1}{\sqrt{1-x^{2}}}\right)=\frac{1}{\sqrt{1-x^{2}}}}\right.\)…
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