Another curious identity
Geometry
Level
3
\[\large \cos(12^\circ)+\cos(84^\circ)+\cos(132^\circ)+\cos(156^\circ)= \ ? \]
Extra Credit Problem: Can you generalize this result by writing an analogous equation involving \(\cos\left(\frac{360^\circ}{n}\right)\) for any positive integer \(n\)?
by
Otto Bretscher