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  2. Principal axis theorem - Wikipedia

    en.wikipedia.org/wiki/Principal_axis_theorem

    The basic observation is that if, by completing the square, the quadratic expression can be reduced to a sum of two squares then the equation defines an ellipse, whereas if it reduces to a difference of two squares then the equation represents a hyperbola: (,) + (,) = (,) (,) =.

  3. 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.

  4. Ellipsoid - Wikipedia

    en.wikipedia.org/wiki/Ellipsoid

    The reverse scaling (see above) transforms the unit sphere back to the ellipsoid and the vectors e 0, e 1, e 2 are mapped onto vectors f 0, f 1, f 2, which were wanted for the parametric representation of the intersection ellipse. How to find the vertices and semi-axes of the ellipse is described in ellipse.

  5. 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 ...

  6. Superellipse - Wikipedia

    en.wikipedia.org/wiki/Superellipse

    Examples of superellipses for =, =. A superellipse, also known as a Lamé curve after Gabriel Lamé, is a closed curve resembling the ellipse, retaining the geometric features of semi-major axis and semi-minor axis, and symmetry about them, but defined by an equation that allows for various shapes between a rectangle and an ellipse.

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

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

    The semi-minor axis of an ellipse runs from the center of the ellipse (a point halfway between and on the line running between the foci) to the edge of the ellipse. The semi-minor axis is half of the minor axis. The minor axis is the longest line segment perpendicular to the major axis that connects two points on the ellipse's edge.

  8. Matrix representation of conic sections - Wikipedia

    en.wikipedia.org/wiki/Matrix_representation_of...

    The vertices of a central conic can be determined by calculating the intersections of the conic and its axes — in other words, by solving the system consisting of the quadratic conic equation and the linear equation for alternately one or the other of the axes. Two or no vertices are obtained for each axis, since, in the case of the hyperbola ...

  9. Finding Ellipses - Wikipedia

    en.wikipedia.org/wiki/Finding_Ellipses

    Finding Ellipses: What Blaschke Products, Poncelet’s Theorem, and the Numerical Range Know about Each Other is a mathematics book on "some surprising connections among complex analysis, geometry, and linear algebra", [1] and on the connected ways that ellipses can arise from other subjects of study in all three of these fields. [2]