Answer:
60°
Step-by-step explanation:
In a circumscribed quadrilateral, opposite angles are supplementary.
x° = 180° -120°
x° = 60°
_____
Derivation of the relationship
Arcs BAD and BCD have a sum of 360°. Arc BAD is twice the measure of angle BCD. Likewise, arc BCD is twice the measure of angle BAD. So, we have ...
2∠BCD +2∠BAD = 360°
∠BCD +∠BAD = 180° . . . . . . divide by 2. This is the relation we used above.
