Sorry, but what context are we talking about? Perhaps you were referring to the history of the term “Viewing Angle”?
Okay, let's try to write an article about what "visual angle" is and how it differs from visual angle. I hope this helps you learn more about this term.
Visual angle (English visual angle, English-Russian visual angles) is the geometric angle between two points at the edges of a given area of the visual field, considered as a plane. Indicated in degrees. Represents the amount of space with which we perceive visual