Use the intersecting chords theorem to calculate the radius of the circle.
(Extend CO to meet the circle again at A, then AE.EC = BE.ED .)
That gets you the dimensions of the triangle BOE and you can then use the cosine rule to calculate the angles.
Use the intersecting chords theorem to calculate the radius of the circle.
(Extend CO to meet the circle again at A, then AE.EC = BE.ED .)
That gets you the dimensions of the triangle BOE and you can then use the cosine rule to calculate the angles.