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  2. Elliptic coordinate system - Wikipedia

    en.wikipedia.org/wiki/Elliptic_coordinate_system

    In geometry, the elliptic coordinate system is a two-dimensional orthogonal coordinate system in which the coordinate lines are confocal ellipses and hyperbolae. The two foci F 1 {\displaystyle F_{1}} and F 2 {\displaystyle F_{2}} are generally taken to be fixed at − a {\displaystyle -a} and + a {\displaystyle +a} , respectively, on the x ...

  3. Ellipsoidal coordinates - Wikipedia

    en.wikipedia.org/wiki/Ellipsoidal_coordinates

    Ellipsoidal coordinates are a three-dimensional orthogonal coordinate system (,,) that generalizes the two-dimensional elliptic coordinate system. Unlike most three-dimensional orthogonal coordinate systems that feature quadratic coordinate surfaces , the ellipsoidal coordinate system is based on confocal quadrics .

  4. Ellipse - Wikipedia

    en.wikipedia.org/wiki/Ellipse

    An ellipse (red) obtained as the intersection of a cone with an inclined plane. Ellipse: notations Ellipses: examples with increasing eccentricity. In mathematics, an ellipse is a plane curve surrounding two focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant.

  5. Elliptic geometry - Wikipedia

    en.wikipedia.org/wiki/Elliptic_geometry

    The distance formula is homogeneous in each variable, with d(λu, μv) = d(u, v) if λ and μ are non-zero scalars, so it does define a distance on the points of projective space. A notable property of the projective elliptic geometry is that for even dimensions, such as the plane, the geometry is non-orientable. It erases the distinction ...

  6. Elliptic curve - Wikipedia

    en.wikipedia.org/wiki/Elliptic_curve

    Then the K-rational points of E are the points on E whose coordinates all lie in K, including the point at infinity. The set of K -rational points is denoted by E ( K ) . E ( K ) is a group, because properties of polynomial equations show that if P is in E ( K ) , then − P is also in E ( K ) , and if two of P , Q , R are in E ( K ) , then so ...

  7. Earth ellipsoid - Wikipedia

    en.wikipedia.org/wiki/Earth_ellipsoid

    Geodetic coordinates P(ɸ,λ,h) Geodetic coordinates are a type of curvilinear orthogonal coordinate system used in geodesy based on a reference ellipsoid. They include geodetic latitude (north/south) ϕ, longitude (east/west) λ, and ellipsoidal height h (also known as geodetic height [8]).

  8. Elliptic cylindrical coordinates - Wikipedia

    en.wikipedia.org/wiki/Elliptic_cylindrical...

    Coordinate surfaces of elliptic cylindrical coordinates. The yellow sheet is the prism of a half-hyperbola corresponding to ν=-45°, whereas the red tube is an elliptical prism corresponding to μ=1. The blue sheet corresponds to z=1.

  9. Semi-major and semi-minor axes - Wikipedia

    en.wikipedia.org/wiki/Semi-major_and_semi-minor_axes

    where (h, k) is the center of the ellipse in Cartesian coordinates, in which an arbitrary point is given by (x, y). The semi-major axis is the mean value of the maximum and minimum distances r max {\displaystyle r_{\text{max}}} and r min {\displaystyle r_{\text{min}}} of the ellipse from a focus — that is, of the distances from a focus to the ...