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  2. Orthoptic (geometry) - Wikipedia

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

    In the case of an ellipsex 2 / a 2 ⁠ + ⁠ y 2 / b 2 ⁠ = 1 one can adopt the idea for the orthoptic for the quadratic equation + = Now, as in the case of a parabola, the quadratic equation has to be solved and the two solutions m 1 , m 2 must be inserted into the equation tan 2 ⁡ α = ( m 1 − m 2 1 + m 1 m 2 ) 2 . {\displaystyle ...

  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. Eccentricity (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Eccentricity_(mathematics)

    A family of conic sections of varying eccentricity share a focus point F and directrix line L, including an ellipse (red, e = 1/2), a parabola (green, e = 1), and a hyperbola (blue, e = 2). The conic of eccentricity 0 in this figure is an infinitesimal circle centered at the focus, and the conic of eccentricity ∞ is an infinitesimally ...

  5. File:Ellipse Properties of Directrix and String Construction ...

    en.wikipedia.org/wiki/File:Ellipse_Properties_of...

    *The distance from a point, P, on the ellipse to a focus is always proportional to the distance to a vertical line, D, called the directrix. The constant of proportionality is the eccentricity, e. *The eccentricity is always between 0 and 1. At zero, the ellispe becomes a circle, at 1 the ellipse becomes a parabola. Greater than one, it is a ...

  6. 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 ...

  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. Perimeter of an ellipse - Wikipedia

    en.wikipedia.org/wiki/Perimeter_of_an_ellipse

    An ellipse has two axes and two foci. Unlike most other elementary shapes, such as the circle and square, there is no algebraic equation to determine the perimeter of an ellipse. Throughout history, a large number of equations for approximations and estimates have been made for the perimeter of an ellipse.

  9. Director circle - Wikipedia

    en.wikipedia.org/wiki/Director_circle

    More generally, for any collection of points P i, weights w i, and constant C, one can define a circle as the locus of points X such that (,) =.. The director circle of an ellipse is a special case of this more general construction with two points P 1 and P 2 at the foci of the ellipse, weights w 1 = w 2 = 1, and C equal to the square of the major axis of the ellipse.