Find the value of x in the following figure, where O is the centre of the circle:

Find the value of x in the following figure, where O is the centre of the circle:

Step 1: Recognize that ∠AOB is the central angle subtending the arc (AB).
Step 2: Angles subtended by the same arc in the circumference are half of the central angle.
Therefore, the angle subtended by arc (AB) at point (D), i.e., ∠ADC = `1/2 ∠AOB = 1/2 "times" 30° = 15°`
Thus, the value of x = 15