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Understand how to calculate a circle's area with the help of chain and ruler
Eccentricity of conic sectionsThe eccentricity of a conic section completely characterizes its shape. For example, all circles have zero eccentricity, and all parabolas have unit eccentricity; hence, all circles (and all parabolas) have the same shape, only varying in size. (Under appropriate magnification they are indistinguishable.) In contrast, ellipses and hyperbolas vary greatly in shape. transformation of a circular region into an approximately rectangular region Figure 11: Beltrami's circle model. Concentric circles and infinity Diagram showing a double cone intersected by planes at different angles, producing the conic sections: a horizontal plane creates a circle, a tilted plane creates an ellipse, a plane parallel to the cone's side forms a parabola, and a steep plane produces a hyperbola. Each section is labeled, with the axis and apex of the cone indicated. A diagram of a double cone intersected by two green planes labeled PP (picture plane) and RP (reality plane), illustrating projected conic sections in projective geometry, with the apex and a point Omega marked. Figure 5: Intersecting circles. If a circle with centre A has a point X inside, as well as a point Y outside, a second circle with centre B, and if X and Y lie on AB, then the circles have at least one common point on each side of AB. Chord in a circle Pascal's projective theoremThe 17th-century French mathematician Blaise Pascal proved that the three points (x, y, z) formed by intersecting the six lines that connect any six distinct points (A, B, C, D, E, F) on a circle are collinear.
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Equations written on blackboard
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Italian-born physicist Dr. Enrico Fermi draws a diagram at a blackboard with mathematical equations. circa 1950.
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circle: References & Edit History

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Article History

Type Description Contributor Date
Modified link of Web site: Mathematics LibreTexts - Circles. Sep 04, 2026
Add new Web site: LOUIS Pressbooks - Trigonometry - Circles. Jun 12, 2026
Add new Web site: Australian Mathematical Sciences Institute - Circle Geometry. Aug 31, 2024
Add new Web site: Australian Mathematical Sciences Institute - The Circle. May 24, 2024
Add new Web site: Open Library Publishing Platform - The Living Tree of Mathematics: Math Problems through World History and Cultures - Circles. Apr 12, 2024
Add new Web site: BCcampus Open Publishing - Introduction to Drafting and AutoCAD 2D - Circles and Arcs. Feb 29, 2024
Add new Web site: Academia - Circle As A Symbol of Power In Architecture. Aug 22, 2023
Add new Web site: Story of Mathematics - Circles οΏ½ Explanation and Examples. Jun 16, 2023
Add new Web site: Mathematics LibreTexts - Circles. Dec 30, 2022
Add new Web site: Khan Academy - Circles. Sep 29, 2022
Added video about the area of a circle. Dec 03, 2015
Add new Web site: Kids Math - Circle. Mar 21, 2012
Add new Web site: Wolfram MathWorld - Circle. Nov 18, 2011
Add new Web site: Fact Monster - Science - Circle. Nov 16, 2011
Add new Web site: Maths Is Fun - Circle. Nov 16, 2011
New article added. Feb 20, 2009
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