Editing Nine-point circle (section)

== External links ==
*[https://www.geogebra.org/m/kzabj78a Nine-point circle] - interactive illustration of the nine-point circle and some of its properties
*[https://rykap.com/nine_point_circle/index.html "A Javascript demonstration of the nine point circle"] at rykap.com
*[https://faculty.evansville.edu/ck6/encyclopedia/ETC.html ''Encyclopedia of Triangles Centers''] by Clark Kimberling.  The nine-point center is indexed as X(5), the Feuerbach point, as X(11), the center of the Kiepert hyperbola as X(115), and the center of the Jeřábek hyperbola as X(125).
* History about the nine-point circle based on J.S. MacKay's article from 1892: [http://jwilson.coe.uga.edu/EMT668/EMT668.Folders.F97/Anderson/geometry/geometry1project/historyofninepointcircle/history.html History of the Nine Point Circle]
* {{mathworld|urlname=Nine-PointCircle|title=Nine-Point Circle}}
* {{mathworld|urlname=Orthopole|title=Orthopole}}
* [https://www.cut-the-knot.org/Curriculum/Geometry/SixPointCircle.shtml Nine Point Circle] at [[cut-the-knot]]
* [https://demonstrations.wolfram.com/TheCenterAndRadiusOfTheNinePointCircle/ Interactive Nine Point Circle applet] from the Wolfram Demonstrations Project
* [https://dynamicmathematicslearning.com/ninepointconic.html Nine-point conic and Euler line generalization] at [http://dynamicmathematicslearning.com/JavaGSPLinks.htm Dynamic Geometry Sketches] Generalizes nine-point circle to a nine-point conic with an associated generalization of the Euler line.
* [https://arxiv.org/pdf/0806.3617.pdf N J Wildberger. Chromogeometry.] Discusses the nine-point circle with regard to three different quadratic forms (blue, red, green).

[[Category:Circles defined for a triangle]]