As shown in the figure, it is known that △ ABC is inscribed in circle O, AE bisects ∠ BAC, and ad ⊥ BC is at point D. connect OA, and verify ∠ OAE = ∠ DAE As shown in the figure, it is known that △ ABC is inscribed in circle O, AE bisects ∠ BAC, and ad ⊥ BC is connected to point D, OA is connected, and the verification is as follows: ∠ OAE = ∠ DAE

As shown in the figure, it is known that △ ABC is inscribed in circle O, AE bisects ∠ BAC, and ad ⊥ BC is at point D. connect OA, and verify ∠ OAE = ∠ DAE As shown in the figure, it is known that △ ABC is inscribed in circle O, AE bisects ∠ BAC, and ad ⊥ BC is connected to point D, OA is connected, and the verification is as follows: ∠ OAE = ∠ DAE

(3) because AF is diameter, so ACF is right angle, so fac and CFA complement each other. (1) because ad is perpendicular to BC, so ABC and bad complement each other. (2) from (1) (2) (3), angle bad = angle CaF (equivalent substitution) because AE bisects ∠ BAC, that is, angle B