A, B, G iHaiit les angles d'un triangle, on a

Ig A + ts; B + tg C ^ tg A tg B tg C,

a [1 + cos A cos B cos C) ^ sin' A + sin» B + sin' C,

sin A cos B 003 C + sin B cos G cos A + sin C cos A cos B — sin A sin B sin C,

cosAsinBsinC + cOBBsinCsinA+cosCsiaAsinB = H-cosAcosBcosC,

sin» A sin (B - C) + sin' B sin (C - A] + sin^ C sin {A - B) = 0,

sin! A cos (B - C) + sin' B cos {C - A) + sin> C cos (A - B) = 3 sin A sin B hin C.