The chord AB is equal to the radius of the circle.
OA and OB are the two radii of the circle.
AB = OA = OB = radius of the circle.
ΔOAB is an equilateral triangle.
AOC = 60°
And, ACB = ½ AOB
So, ACB = ½ × 60° = 30°
Now, ACBD is a cyclic quadrilateral,
ADB +ACB = 180° (Since they are the opposite angles of a cyclic quadrilateral)
So, ADB = 180°-30° = 150°
Hence, the angle subtended by the chord at a point on the minor arc and also at a point on the major arc is 150° and 30° respectively.