出典:Wiktionary
出典:『Wiktionary』 (2026/03/22 21:02 UTC 版)
surface area (countable and uncountable, plural surface areas)
出典:Wikipedia
出典:『Wikipedia』 (2011/07/22 17:26 UTC 版)
Surface area is the measure of how much exposed area a solid object has, expressed in square units. Mathematical description of the surface area is considerably more involved than the definition of arc length of a curve. For polyhedra (objects with flat polygonal faces) the surface area is the sum of the areas of its faces. Smooth surfaces, such as a sphere, are assigned surface area using their representation as parametric surfaces. This definition of the surface area is based on methods of infinitesimal calculus and involves partial derivatives and double integration.