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Math geometry problems in the seventh grade of junior high school.
Proof: ∫BO equally divided ∠ABC

∴∠ABO=∠OBC

∫CE sharing∠ ∠ACB

∴∠ACO=∠OCB

∫ Germany∨ BC

∴∠BOD=∠OBC ∠EOC=∠OEB (two parallel lines have the same internal angle)

∠∠ ABO =∠OBC∠ ACO =∠OCB.

∴∠ABO=∠DOB ∠EOC=∠ACO (equivalent substitution)

That is, △DBO and △ECO are isosceles triangles.

∴ DB = DOEC = Council of Europe

∫BD+EC = 5

∴BD+EC=DO+OE=5

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