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A sphere of radius r has surface area 4πr 2.. The surface area (symbol A) of a solid object is a measure of the total area that the surface of the object occupies. [1] The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of arc length of one-dimensional curves, or of the surface area for polyhedra (i.e., objects with ...
The sphere has the smallest surface area of all surfaces that enclose a given volume, and it encloses the largest volume among all closed surfaces with a given surface area. [11] The sphere therefore appears in nature: for example, bubbles and small water drops are roughly spherical because the surface tension locally minimizes surface area.
The formula for the surface area of a sphere is more difficult to derive: because a sphere has nonzero Gaussian curvature, it cannot be flattened out. The formula for the surface area of a sphere was first obtained by Archimedes in his work On the Sphere and Cylinder. The formula is: [6] A = 4πr 2 (sphere), where r is the radius of the sphere.
A Rorschach test is a figure invariant by this symmetry, [203] as are butterfly and animal bodies more generally (at least on the surface). [204] Waves on the sea surface possess translation symmetry: moving one's viewpoint by the distance between wave crests does not change one's view of the sea. [205] Fractals possess self-similarity. [206] [207]
More generally, the lateral surface area of a prism is the sum of the areas of the sides of the prism. [1] This lateral surface area can be calculated by multiplying the perimeter of the base by the height of the prism. [2] For a right circular cylinder of radius r and height h, the lateral area is the area of the side surface of the cylinder ...
A special type of area density is called column density (also columnar mass density or simply column density), denoted ρ A or σ.It is the mass of substance per unit area integrated along a path; [1] It is obtained integrating volumetric density over a column: [2] =.
The surface area can be calculated by integrating the length of the normal vector to the surface over the appropriate region D in the parametric uv plane: = | |. Although this formula provides a closed expression for the surface area, for all but very special surfaces this results in a complicated double integral , which is typically evaluated ...
For any surface embedded in Euclidean space of dimension 3 or higher, it is possible to measure the length of a curve on the surface, the angle between two curves and the area of a region on the surface. This structure is encoded infinitesimally in a Riemannian metric on the surface through line elements and area elements.