Name the major arc and find its measure

The largest arch for this case is the ADB arch.
 To know the size of the major arc, the first thing you should keep in mind is that the entire circumference measures 360 degrees.
 We then have the following equation:
 ADB + 50 = 360
 From here, we clear the value of ADB.
 We have then:
 ADB = 360 - 50
 ADB = 310 degrees.
 
 The measure of the major arc is:
 ADB = 310 degrees.