Trigonometrikus azonosság
- Author:
- Száldobágyi Zsigmond
Forrás:
Alexander Bogomolny, A Quick Proof of cos(pi/7)cos(2.pi/7)cos(3.pi/7)=1/8 from Interactive Mathematics Miscellany and Puzzles
https://www.cut-the-knot.org/pythagoras/CosCosCos.shtml, Accessed 10 May 2018