GEOS circle
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The GEOS Circle is derived from the intersection of 4 lines that are associated with a generalized triangle; The Euler line, Soddy line, orthic axis and Gergonne line. Note that the Euler line is orthogonal to the Orthic axis and that the Soddy line is orthogonal to the Gergonne line.
These 4 lines provide 6 points of intersection of which 2 points intersect orthogonally consequently the other 4 points form an orthocentric system.
The GEOS circle is that circle centered at a point equidistant from X650 (the intersection of the Orthic axis with the Gergonne line) and X20 (the intersection of the Euler line with the Soddy line and is known as the de Longchamps point) and passes through these points as well as the 2 points of orthogonal intersection.
The orthogonal intersection points are X468 (the intersection of the Orthic axis with the Euler line) and X1323 (the intersection of the Gergonne line with the Soddy line and is known as the Fletcher point).
The orthocentric system comprises X650, X20, X1375 (the intersection of the Euler line with the Gergonne line and is known as the Evans point) and X3012 (the intersection of the Soddy line and the Orthic axis).
The X(i) point notation is the Clark Kimberling ETC classification of triangle centers.
[edit] References
- Eric W. Weisstein, GEOS Circle at MathWorld.
- Clark Kimberling, "Encyclopedia of triangle centers". (Lists some 3000 interesting points associated with any triangle.)
