Prove:
∵ parallel to AO and OE⊥OA.
∴ Quadrilateral AOEB is a rectangle.
∴∠BOE and ∠2 are complementary, while ∠∠ BOE and ∠ 3 are complementary.
∴∠2=∠3
∴∠ 1=∠3 - ①
∠∠ EOH =180-∠AOE-∠1,and ∠ AOE is a right angle.
∴∠EOH and∠1are complementary, and∠ 4 and∠ EOH are known to be complementary.
∴∠ 1=∠4 - ②
Pass conditions ① and ②.
∴∠3=∠4