Proof
Proof. D and E are the middle points of AB and AC, DE intersects the circle at G and F, CF // AB. Prove: CD = BC; Δ BCD ~ Δ GBD. Prove: 1. CD = BC. Prove: 1. CD = BC Because AD = DB, AE = EC. Prove: 1. CD = BC Because AD = DB, AE = EC Then DE // BC.
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