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  2. Four-dimensional space - Wikipedia

    en.wikipedia.org/wiki/Four-dimensional_space

    For example, consider the formulas for the area enclosed by a circle in two dimensions (=) and the volume enclosed by a sphere in three dimensions (=). One might guess that the volume enclosed by the sphere in four-dimensional space is a rational multiple of π r 4 {\displaystyle \pi r^{4}} , but the correct volume is π 2 2 r 4 {\displaystyle ...

  3. Dioptre - Wikipedia

    en.wikipedia.org/wiki/Dioptre

    Illustration of the relationship between optical power in dioptres and focal length in metres. A dioptre (British spelling) or diopter (American spelling), symbol dpt, is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, 1 dpt = 1 m −1.

  4. End correction - Wikipedia

    en.wikipedia.org/wiki/End_correction

    The analysis above applies only to an ideal tube, of zero diameter. When designing an organ or Boomwhacker, the diameter of the tube must be taken into account. In acoustics, end correction is a short distance applied or added to the actual length of a resonance pipe, in order to calculate the precise resonant frequency of the pipe. The pitch ...

  5. Standard error - Wikipedia

    en.wikipedia.org/wiki/Standard_error

    This approximate formula is for moderate to large sample sizes; the reference gives the exact formulas for any sample size, and can be applied to heavily autocorrelated time series like Wall Street stock quotes. Moreover, this formula works for positive and negative ρ alike. [12] See also unbiased estimation of standard deviation for more ...

  6. Prism (geometry) - Wikipedia

    en.wikipedia.org/wiki/Prism_(geometry)

    In geometry, a prism is a polyhedron comprising an n-sided polygon base, a second base which is a translated copy (rigidly moved without rotation) of the first, and n other faces, necessarily all parallelograms, joining corresponding sides of the two bases.

  7. Volume of an n-ball - Wikipedia

    en.wikipedia.org/wiki/Volume_of_an_n-ball

    The volume can be computed without use of the Gamma function. As is proved below using a vector-calculus double integral in polar coordinates, the volume V of an n-ball of radius R can be expressed recursively in terms of the volume of an (n − 2)-ball, via the interleaved recurrence relation:

  8. Formula - Wikipedia

    en.wikipedia.org/wiki/Formula

    A molecular formula enumerates the number of atoms to reflect those in the molecule, so that the molecular formula for glucose is C 6 H 12 O 6 rather than the glucose empirical formula, which is CH 2 O. Except for the very simple substances, molecular chemical formulas generally lack needed structural information, and might even be ambiguous in ...

  9. Quadratic equation - Wikipedia

    en.wikipedia.org/wiki/Quadratic_equation

    In mathematics, a quadratic equation (from Latin quadratus 'square') is an equation that can be rearranged in standard form as [1] + + =, where x represents an unknown value, and a, b, and c represent known numbers, where a ≠ 0.