If one ray of an angle lies on 0, then the measure of the angle will be the number corresponding to the other ray of the angle. [br][br]In the picture, since OB lies on 0, the measure of <AOB will be the measure corresponding to OA. Which is...?[br][br]This is written as m<AOB and said "the measure of angle AOB."[br][br]If one of the rays of the angle does not lie on 0, then the angle measure will be the difference in the number corresponding to the rays.