Simple but often unknown theorems/lemmas/formula? Do you know?

Revision en1, by duckladydinh, 2017-11-20 20:32:45

Hallo everyone,

Do you know any simple formulas that are often unknown to many? For me, some can be mentioned are Euler characteristic, 2-Ear Theorem, Pigeonhole, Fermat, Handshaking theorem, incenter formula of a triangle... And what about you? Can you share some?

Thank you.

History

 
 
 
 
Revisions
 
 
  Rev. Lang. By When Δ Comment
en8 English duckladydinh 2017-11-28 04:39:46 37 Tiny change: 'orem\n\n- ' -> 'orem\n\n- Fibonacci: Zeckendorf's theorem\n\n- '
en7 English duckladydinh 2017-11-28 04:38:34 392 Tiny change: '- Graph:\n- - Euler c' -> '- Graph:\n - Euler c'
en6 English duckladydinh 2017-11-23 08:15:37 24
en5 English duckladydinh 2017-11-23 08:15:14 60
en4 English duckladydinh 2017-11-22 00:22:47 18 Tiny change: 'ce Formula... And wh' -> 'ce Formula, McNugget theorem... And wh'
en3 English duckladydinh 2017-11-22 00:19:13 19 Tiny change: 'ck theorem... And wh' -> 'ck theorem, Shoelace Formula... And wh'
en2 English duckladydinh 2017-11-20 23:11:19 35 Tiny change: 'a triangle... And wh' -> 'a triangle, harmonic series sum, pick theorem... And wh'
en1 English duckladydinh 2017-11-20 20:32:45 344 Initial revision (published)