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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. Eccentric anomaly - Wikipedia

    en.wikipedia.org/wiki/Eccentric_anomaly

    Consider the ellipse with equation given by: + =, where a is the semi-major axis and b is the semi-minor axis. For a point on the ellipse, P = P(x, y), representing the position of an orbiting body in an elliptical orbit, the eccentric anomaly is the angle E in the

  4. 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.

  5. Steiner ellipse - Wikipedia

    en.wikipedia.org/wiki/Steiner_ellipse

    The Steiner ellipse has the least area of any ellipse circumscribed about the triangle. [1] The Steiner ellipse is the scaled Steiner inellipse (factor 2, center is the centroid). Hence both ellipses are similar (have the same eccentricity).

  6. Elliptic integral - Wikipedia

    en.wikipedia.org/wiki/Elliptic_integral

    For an ellipse with semi-major axis a and semi-minor axis b and eccentricity e = √ 1 − b 2 /a 2, the complete elliptic integral of the second kind E(e) is equal to one quarter of the circumference C of the ellipse measured in units of the semi-major axis a. In other words: = ().

  7. Roundness - Wikipedia

    en.wikipedia.org/wiki/Roundness

    Roundness = ⁠ Perimeter 2 / 4 π × Area ⁠. This ratio will be 1 for a circle and greater than 1 for non-circular shapes. Another definition is the inverse of that: Roundness = ⁠ 4 π × Area / Perimeter 2 ⁠, which is 1 for a perfect circle and goes down as far as 0 for highly non-circular shapes.

  8. Orbital eccentricity - Wikipedia

    en.wikipedia.org/wiki/Orbital_eccentricity

    For elliptical orbits, a simple proof shows that ⁡ gives the projection angle of a perfect circle to an ellipse of eccentricity e. For example, to view the eccentricity of the planet Mercury (e = 0.2056), one must simply calculate the inverse sine to find the projection angle of 11.86 degrees. Then, tilting any circular object by that angle ...

  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