Solution: Angle AOC is the central angle of arc AC, and angle B is the central angle of arc AC.

∴ Angle B= 1/2 Angle AOC = 6 1■

∵ The quadrilateral ABCD is inscribed in the circle O, so the angle B+ the angle ADC = 180.

∴ADC = 180-6 1 = 1 19。

EDC = ADE-ADC = 180- 1 19 = 6 1。

To sum up: angle B= angle EDC = 6 1.

In fact, there is a conclusion: the outer angle of each corner of the inscribed quadrangle of a circle is equal to the angle opposite to this angle.

Is there a problem? Please adopt