text: SURFACE AREA\n\n\nSurface area is the area of a given surface. Roughly speaking, it is the "amount" of a surface (i.e., it is proportional to the amount of paint needed to cover it), and has units of distance squared. Surface area is commonly denoted  for a surface in three dimensions, or  for a region of the plane (in which case it is simply called "the" area). \n\n\n\n\nSurface area refers to the summation of the areas of the exposed sides of an object.\n\nUnits\nUnits for measuring surface area include:\n\nsquare metre = SI derived unit \nare = 100 square metres \nhectare = 10,000 square metres \nsquare kilometre = 1,000,000 square metres \nsquare megametre = 1012 square metres \nImperial units, as currently defined from the metre:\n\nsquare foot (plural square feet) = 0.09290304 square metres. \nsquare yard = 9 square feet = 0.83612736 square metres \nsquare perch = 30.25 square yards = 25.2928526 square metres \nacre = 160 square perches or 43,560 square feet = 4046.8564224 square metres \nsquare mile = 640 acres = 2.5899881103 square kilometres \nThe article Orders of magnitude links to lists of objects of comparable surface area.\n\n\nUseful formulae\nArea of a rectangle (and, in particular, a square): length × width \nArea of a triangle: ½ × base × height \nArea of a disk: π × r² \nArea of a sphere: 4 × π × r² \nTotal surface area of a right circular cylinder: 2 × π × r × (h + r) \nLateral surface area of a right circular cylinder: 2 × π × r × h \nTotal surface area of a right circular cone: π × r × (l + r) \nLateral surface area of a right circular cone: π × r × l