Q. If$\ 4n\alpha = \ \pi,\$then the value of $\tan{\alpha \bullet \tan{2\alpha \bullet \tan{3\alpha \bullet \tan\ 4\alpha\ldots\tan{(2n - 2)\alpha\ }}}}\tan{(2n - 1)}\alpha$ is

A) 0
B) 1
C) $- 1$
D) None of these
Explanation

(b)
$\tan{\alpha\tan{2\alpha\ldots\tan{(2n - 1)\alpha\tan{(2n - 1)\alpha}}}}$
$= \left\{ \tan{\alpha\tan{(2n - 1)\alpha}} \right\}\left\{ \tan{2\alpha\tan{(2n - 2)\alpha}} \right\}\ldots\left\{ \tan{(n - 1)\alpha\tan{(n + 1)\alpha}} \right\}\tan{n\alpha}$
$= \left\{ \tan{\alpha\tan\left( \frac{\pi}{2} - \alpha \right)} \right\}\left\{ \tan{2\alpha\tan\left( \frac{\pi}{2} - 2\alpha \right)} \right\}\ldots\tan\frac{\pi}{4}\ \ \left( \because n\alpha = \frac{\pi}{4} \right)$
$= 1$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.