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Mathematics rectangle of grade three
Abcd is a rectangle, ∴∠ bad = 90.

Ab cd intersects at point o, ∴ AO=CO=BO=DO.

∫AE bisects ∠ ∠BAD intersects BC at point E∴∠ BAE =∠ EAD = 45.

* EAC = 15 ∴∠ba0=60

AO = BO

∴∠ABO=60

∵∠Bao+∠ABO+∠AOB = 180 ∴∠aob=60

△ AOB is an equilateral triangle.

That is AB=OA=BO.

∠∠ABC = 90∠EAB = 45。

∠ABC+∠ea b+∠bea = 180 ∴∠bea=45

∴△ABE is an isosceles right triangle.

∴ BE=BA

∵ BE=BA and BA=BO ∴BE=BO.

That is, △OBE is isosceles △

∠∠ABC = 90∠ABO = 60

∴∠OBE=30

∴∠BOE=∠BEO=( 180-30)÷2=75