The measure of AB is 57.5 degrees
How to get the angle
A minor arc is a portion of a circle's circumference that spans less than or equal to 180 degrees. It is formed by two points on the circle and the arc between those points, typically denoted by naming the endpoints.
In comparison to a major arc, which spans more than 180 degrees of a circle's circumference, a minor arc covers the shorter distance between two points on the circle.
The angle AB is the minor arc
The measure of AB is angle at the center / 2
= 115 / 2
= 57.5 degrees