Answer:
Functional Areas are areas that are not clearly defined by borders but have consist of a focal point and then the surrounding areas attached to it. A Metropolitan area is an example of a functional Area.
Formal Area is recognized as an area that has a clear and official border surrounding it to demarcate it from other areas. These include; cities, towns, states, Countries.
Perceptual Region is one that has no boundaries but refers to the people in a general area that share the same characteristics be it in terms of culture, climate, location on the map and the like. For example, North America is a perceptual region. These characteristics are not always absolute ans can be relative based on people's perception of an area.
Functional Areas
Formal Areas
Perceptual Region