It is known that: as shown in the figure, AB is the diameter of ⊙ o, AC is the chord, CD ⊥ AB at D. if AE = AC, be intersects ⊙ o at point F, CF and de are connected

It is known that: as shown in the figure, AB is the diameter of ⊙ o, AC is the chord, CD ⊥ AB at D. if AE = AC, be intersects ⊙ o at point F, CF and de are connected

It is proved that: (1) connecting BC, ∵ AB is the diameter of ⊙ o, ∵ ACB = 90 °∵ CD ⊥ AB, ∵ ACD ∵ ABC. ∵ Acad = ABAC. ∵ AC = AE, ∵ AE2 = ad ∵ ab. (2) ∵ AE2 = ad ∵ AB, ∵ ead = ∵ Bae, ∵ ade ∵ AEB. ∵ AED = ∵ B. ∵ ACF = ? B, ? ACF = ? AED