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MHT CET · Maths · Inverse Trigonometric Functions

If \(\tan ^{-1}\left(\frac{1-x}{1+x}\right)=\frac{1}{2} \tan ^{-1} x\), then \(x\) is

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

Answer & Solution

Correct Answer

(C) \(\frac{1}{\sqrt{3}}\)

Step-by-step Solution

Detailed explanation

\(\begin{aligned} & \tan ^{-1}\left(\frac{1-x}{1+x}\right)=\frac{1}{2} \tan ^{-1} x \\ & \Rightarrow \tan ^{-1}(1)-\tan ^{-1}(x)=\frac{1}{2} \tan ^{-1} x \\ & \Rightarrow \frac{\pi}{4}=\frac{3}{2} \tan ^{-1} x \\ & \Rightarrow x=\tan \left(\frac{\pi}{6}\right)=\frac{1}{\sqrt{3}}\end{aligned}\)