perimeter, volume and or area are useful to a designer because he or she would have to know what size to cut materials to fit on the project correctly. if they do not know these thing before they begin putting together the project it won't come out correctly it could come out larger or smaller and even wider than expected. these things would be useful for a landscaper, a boy who mows the lawn and a painter. but it would obviously be most helpful to a carpenter. this is true because when they are building houses and tree houses they will need to know these things to make the house safe.