The chord of a circle is equal to its radius. The angle (in degrees) subtended by this chord at any point on the minor arc of the circle is:

Correct option is C

Given:

A chord of a circle is equal in length to the radius of the circle.

Theorem Used:

​The angle subtended by a chord at any point on the minor arc is half the angle subtended by the same chord at the center of the circle.

Solution:

∠ACB = ½ ∠AOB = ½ × 60° = 30°

∠ACB + ∠ADB = 180° (Opposite angles of a cyclic quadrilateral)

∠ADB = 180° - 30° = 150°