MCQ
${\cot ^{ - 1}}3 + {\rm{cose}}{{\rm{c}}^{ - 1}}\sqrt 5  =$
  • A
    $\frac{\pi }{3}$
  • $\frac{\pi }{4}$
  • C
    $\frac{\pi }{6}$
  • D
    $\frac{\pi }{2}$

Answer

Correct option: B.
$\frac{\pi }{4}$
b
(b) ${\cot ^{ - 1}}3 + {\rm{cose}}{{\rm{c}}^{ - 1}}\sqrt 5 = {\cot ^{ - 1}}3 + {\cot ^{ - 1}}2$

$ = {\cot ^{ - 1}}\left( {\frac{{3 \times 2 - 1}}{{3 + 2}}} \right) = {\cot ^{ - 1}}(1) = \frac{\pi }{4}$.

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