MCQ
If ${\tan ^{ - 1}}x - {\tan ^{ - 1}}y = {\tan ^{ - 1}}A,$ then $A$
  • A
    $x - y$
  • B
    $x + y$
  • $\frac{{x - y}}{{1 + xy}}$
  • D
    $\frac{{x + y}}{{1 - xy}}$

Answer

Correct option: C.
$\frac{{x - y}}{{1 + xy}}$
c
(c) Given that ${\tan ^{ - 1}}x - {\tan ^{ - 1}}y = {\tan ^{ - 1}}A$

$ \Rightarrow \,\,{\tan ^{ - 1}}\,\left( {\frac{{x - y}}{{1 + xy}}} \right) = {\tan ^{ - 1}}A$.

Hence $A = \frac{{x - y}}{{1 + xy}}$.

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