∫BD is the bisector, BF = be, BO is the common edge,
∴△BEO≌△BFO →∠EOB=∠FOB=∠COD
∠∠A = 60
∠ EOB =∠ CBO +∠ BCO, BD and CE are angular bisectors.
∫∠EOB = 1/2( 180-60)= 60
∠ COF = 180-∠ FOB -∠ COD = 60.
And ∵CE are bisectors and CO is a common edge.
∠ COF =∠ Chemical oxygen demand = 60 (certification)
∴△COF≌△COD →CF=CD
∴BC=BF+CF=BE+CD