MCQ
If $\tan ^{-1} \frac{a+x}{a}+\tan ^{-1} \frac{a-x}{a}=\frac{\pi}{6}$, then $x^2=$
  • A
    $2 \sqrt{3 a}$
  • B
    $\sqrt{3 a}$
  • $2 \sqrt{3} a ^2$
  • D
    $\sqrt{3} a ^2$

Answer

Correct option: C.
$2 \sqrt{3} a ^2$
(C) $\tan ^{-1} \frac{a+x}{a}+\tan ^{-1} \frac{a-x}{a}=\frac{\pi}{6}$
$\therefore \quad \tan ^{-1}\left(\frac{\frac{a+x}{a}+\frac{a-x}{a}}{1-\frac{a+x}{a} \cdot \frac{a-x}{a}}\right)=\frac{\pi}{6}$
$\therefore \quad \frac{2 a ^2}{x^2}=\tan \frac{\pi}{6}=\frac{1}{\sqrt{3}} \Rightarrow x^2=2 \sqrt{3} a ^2$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free