The diagonals AC and BD of parallelogram ABCD intersect at point O, BF passes through point O, and intersect with AB and CD at points E and f respectively After modification: the diagonal lines AC and BD of parallelogram ABCD intersect at point O, EF passes through point O, and intersects with AB and CD at points E and f respectively
It is proved that in the parallelogram ABCD, Ao = OC, ab ‖ CD
∴∠AEO=∠CFO ∠EAO=∠FCO
∵AO=OC
∴△AEO≌△CFO
∴OF=OE
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