MCQ
If ${\tan ^{ - 1}}x + 2{\cot ^{ - 1}}x = \frac{{2\pi }}{3},$ then $x =$
  • A
    $\sqrt 2 $
  • B
    $3$
  • $\sqrt 3 $
  • D
    $\frac{{\sqrt 3 - 1}}{{\sqrt 3 + 1}}$

Answer

Correct option: C.
$\sqrt 3 $
c
(c) The given equation may be written as

${\tan ^{ - 1}}x + {\cot ^{ - 1}}x + {\cot ^{ - 1}}x = \frac{{2\pi }}{3}$

==> ${\cot ^{ - 1}}x = \frac{{2\pi }}{3} - \frac{\pi }{2}$ = $\frac{\pi }{6}$ 

==> $x = \sqrt 3 $.

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