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The basic quantities describing a sphere (meaning a 2-sphere, a 2-dimensional surface inside 3-dimensional space) will be denoted by the following variables r {\displaystyle r} is the radius, C = 2 π r {\displaystyle C=2\pi r} is the circumference (the length of any one of its great circles ),
Tessellations of euclidean and hyperbolic space may also be considered regular polytopes. Note that an 'n'-dimensional polytope actually tessellates a space of one dimension less. For example, the (three-dimensional) platonic solids tessellate the 'two'-dimensional 'surface' of the sphere.
A surface is a two-dimensional object, such as a sphere or paraboloid. [55] In differential geometry [53] and topology, [49] surfaces are described by two-dimensional 'patches' (or neighborhoods) that are assembled by diffeomorphisms or homeomorphisms, respectively. In algebraic geometry, surfaces are described by polynomial equations. [54]
The standard "physics convention" 3-tuple set (,,) conflicts with the usual notation for two-dimensional polar coordinates and three-dimensional cylindrical coordinates, where θ is often used for the azimuth. [3] Angles are typically measured in degrees (°) or in radians (rad), where 360° = 2 π rad. The use of degrees is most common in ...
The cross product with respect to a right-handed coordinate system. In mathematics, the cross product or vector product (occasionally directed area product, to emphasize its geometric significance) is a binary operation on two vectors in a three-dimensional oriented Euclidean vector space (named here ), and is denoted by the symbol .
The same formula holds for any three-dimensional objects, except that each should be the volume of , rather than its area. It also holds for any subset of R d , {\displaystyle \mathbb {R} ^{d},} for any dimension d , {\displaystyle d,} with the areas replaced by the d {\displaystyle d} -dimensional measures of the parts.
This formula is valid only for configurations that satisfy < < and () <. If sphere 2 is very large such that r 2 ≫ r 1 {\displaystyle r_{2}\gg r_{1}} , hence d ≫ h {\displaystyle d\gg h} and r 2 ≈ d {\displaystyle r_{2}\approx d} , which is the case for a spherical cap with a base that has a negligible curvature, the above equation is ...
The formula for calculating it can be derived and expressed in several ways. Knowing the shortest distance from a point to a line can be useful in various situations—for example, finding the shortest distance to reach a road, quantifying the scatter on a graph, etc.