tan-2-pi-7-tan-2-3pi-7-tan-2-5pi-7-

Question Number 171389 by cortano1 last updated on 14/Jun/22

\tan^{2} (\frac{π}{7}) + \tan^{2} (\frac{3 π}{7}) + \tan^{2} (\frac{5 π}{7}) = ?

Commented by Shrinava last updated on 14/Jun/22

Or \sec^{2} \frac{π}{7} + \sec^{2} \frac{3 π}{7} + \sec^{2} \frac{5 π}{7} = 21