Movatterモバイル変換


[0]ホーム

URL:


Jump to content
WikipediaThe Free Encyclopedia
Search

Ellipse

From Simple English Wikipedia, the free encyclopedia
Not to be confused withEllipsis.
An ellipse obtained as the intersection of acone with a plane.

Anellipse[1] is a shape that looks like anoval or a flattenedcircle.

Ingeometry, anellipse is aplanecurve which results from the intersection of acone by aplane in a way that produces a closed curve.

Circles are special cases of ellipses, created when the cutting plane isperpendicular to the cone's axis.

An ellipse and its properties.
The foci (purple crosses) are at intersects of the major axis (red) and a circle (cyan) of radius equal to the semi-major axis (blue), centred on an end of the minor axis (grey)

A circle has one center, called afocus. An ellipse has two foci.

An ellipse is simply all points on a graph that the sum of the distances from 2 points are the same. For example, an ellipse can be made by putting two pins into cardboard and a circle of string around those two, then putting a pencil in the loop and pulling as far as possible without breaking the string in all directions. The orbits of the planets are ellipses, with the sun at one focus.

Inanalytic geometry the equation of an ellipse is

(xh)2a2+(yk)2b2=1{\displaystyle {\frac {(x-h)^{2}}{a^{2}}}+{\frac {(y-k)^{2}}{b^{2}}}=1}
where the center of the ellipse is (h,k). 2A is the length from each end of the longer skinnier side. 2b is the length of the 2 ends of the short side. A²-B²=C² for c is the length between the foci and the center.


An ellipse can also be expressed as


(xh)2b2+(yk)2a2=1{\displaystyle {\frac {(x-h)^{2}}{b^{2}}}+{\frac {(y-k)^{2}}{a^{2}}}=1}


In this case, it will be taller than it is wide.

Other websites

[change |change source]

References

[change |change source]
  1. fromGreek ἔλλειψιςelleipsis, a "falling short"



Wikimedia Commons has media related toEllipses.
Retrieved from "https://simple.wikipedia.org/w/index.php?title=Ellipse&oldid=9377505"
Categories:
Hidden categories:

[8]ページ先頭

©2009-2025 Movatter.jp