Area 51 is a facility that specializes in research that is Top Secret/Sensitive Compartmented Information.
The formula for the area of a rectangle follows directly from the basic properties of area, and is sometimes taken as a definition or axiom
  The are was the original unit of area in the metric system, with:1 are = 100 square metresThough the are has fallen out of use, the hectare is still commonly used to measure land:1 hectare = 100 ares = 10,000 square metres = 0

