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  2. Parabola - Wikipedia

    en.wikipedia.org/wiki/Parabola

    A consequence is that the equation (in ,) of the parabola determined by 3 points = (,), =,,, with different x coordinates is (if two x coordinates are equal, there is no parabola with directrix parallel to the x axis, which passes through the points) =.

  3. Conic section - Wikipedia

    en.wikipedia.org/wiki/Conic_section

    Define b by the equations c 2 = a 2 − b 2 for an ellipse and c 2 = a 2 + b 2 for a hyperbola. For a circle, c = 0 so a 2 = b 2, with radius r = a = b. For the parabola, the standard form has the focus on the x-axis at the point (a, 0) and the directrix the line with equation x = −a. In standard form the parabola will always pass through the ...

  4. Focus (geometry) - Wikipedia

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

    The ellipse thus generated has its second focus at the center of the directrix circle, and the ellipse lies entirely within the circle. For the parabola, the center of the directrix moves to the point at infinity (see Projective geometry). The directrix "circle" becomes a curve with zero curvature, indistinguishable from a straight line.

  5. 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 ...

  6. Kiepert conics - Wikipedia

    en.wikipedia.org/wiki/Kiepert_conics

    It has been proved that the Kiepert hyperbola is the hyperbola passing through the vertices, the centroid and the orthocenter of the reference triangle and the Kiepert parabola is the parabola inscribed in the reference triangle having the Euler line as directrix and the triangle center X 110 as focus. [1]

  7. Dandelin spheres - Wikipedia

    en.wikipedia.org/wiki/Dandelin_spheres

    However, a parabola has only one Dandelin sphere, and thus has only one directrix. Using the Dandelin spheres, it can be proved that any conic section is the locus of points for which the distance from a point (focus) is proportional to the distance from the directrix. [7]

  8. Focal conics - Wikipedia

    en.wikipedia.org/wiki/Focal_conics

    A: vertex of the red parabola and focus of the blue parabola F: focus of the red parabola and vertex of the blue parabola. In geometry, focal conics are a pair of curves consisting of [1] [2] either an ellipse and a hyperbola, where the hyperbola is contained in a plane, which is orthogonal to the plane containing the ellipse. The vertices of ...

  9. Translation of axes - Wikipedia

    en.wikipedia.org/wiki/Translation_of_axes

    Given the equation + + =, by using a translation of axes, determine whether the locus of the equation is a parabola, ellipse, or hyperbola. Determine foci (or focus), vertices (or vertex), and eccentricity. Solution: To complete the square in x and y, write the equation in the form