MCQ
${\tan ^2}\theta + {\cot ^2}\theta $ is
  • $ \ge 2$
  • B
    $ \le 2$
  • C
    $ \ge - 2$
  • D
    None of these

Answer

Correct option: A.
$ \ge 2$
a
(a) We know that ${\left( {x - \frac{1}{x}} \right)^2} \ge 0 $

$\Rightarrow {x^2} + \frac{1}{{{x^2}}} - 2 \ge 0$

Put $x = \tan \theta \Rightarrow {\tan ^2}\theta + {\cot ^2}\theta \ge 2$.

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