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  2. 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.

  3. Focus (geometry) - Wikipedia

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

    An ellipse can be defined as the locus of points for which the sum of the distances to two given foci is constant. A circle is the special case of an ellipse in which the two foci coincide with each other. Thus, a circle can be more simply defined as the locus of points each of which is a fixed distance from a single given focus.

  4. n-ellipse - Wikipedia

    en.wikipedia.org/wiki/N-ellipse

    In geometry, the n-ellipse is a generalization of the ellipse allowing more than two foci. [1] n-ellipses go by numerous other names, including multifocal ellipse, [2] polyellipse, [3] egglipse, [4] k-ellipse, [5] and Tschirnhaus'sche Eikurve (after Ehrenfried Walther von Tschirnhaus). They were first investigated by James Clerk Maxwell in 1846 ...

  5. Eccentricity (mathematics) - Wikipedia

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

    A family of conic sections of varying eccentricity share a focus point and directrix line, 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 separated ...

  6. Confocal conic sections - Wikipedia

    en.wikipedia.org/wiki/Confocal_conic_sections

    (See Ellipse § Definition as locus of points and Hyperbola § As locus of points.) The foci F 1 , F 2 {\displaystyle F_{1},\,F_{2}} thus determine two pencils of confocal ellipses and hyperbolas. By the principal axis theorem , the plane admits a Cartesian coordinate system with its origin at the midpoint between foci and its axes aligned with ...

  7. Marden's theorem - Wikipedia

    en.wikipedia.org/wiki/Marden's_theorem

    By the Gauss–Lucas theorem, the root of the double derivative p"(z) must be the average of the two foci, which is the center point of the ellipse and the centroid of the triangle. In the special case that the triangle is equilateral (as happens, for instance, for the polynomial p ( z ) = z 3 − 1 ) the inscribed ellipse becomes a circle, and ...

  8. Cancer warning labels on alcohol? It's not that simple.

    www.aol.com/news/cancer-warning-labels-alcohol...

    The country's top doctor wants a new warning added to alcohol that would alert drinkers about links to cancer, but don't expect cigarette-style warning labels any time soon.. U.S. Surgeon General ...

  9. Kepler's laws of planetary motion - Wikipedia

    en.wikipedia.org/wiki/Kepler's_laws_of_planetary...

    The orbit of every planet is an ellipse with the sun at one of the two foci. Kepler's first law placing the Sun at one of the foci of an elliptical orbit Heliocentric coordinate system (r, θ) for ellipse. Also shown are: semi-major axis a, semi-minor axis b and semi-latus rectum p; center of ellipse and its two foci marked by