Answer:
m<1 = ½(b - d)
Step-by-step explanation:
Recall: when two secants intersect to form an exterior angle outside a circle, the measure of the exterior angle equals half of the difference of the major and minor arcs intersected.
Thus, in the problem given,
m<1 is the exterior angle
b and d are the arcs intersected.
Therefore,
m<1 = ½(b - d)