Geodesic
Yff Conics
Journal for geometry and graphics, Tome 12 (2008) no. 1, pp. 23-34.

Voir la notice de l'article provenant de la source Heldermann Verlag

Suppose that $a,b,c$ are algebraic indeterminates and $U=u:v:w$ is a point given in homogeneous trilinear coordinates. The Yff conic of $U$ is defined as the locus of a point $X=x:y:z$ satisfying the equation $f(x,y,z) = f(u,v,w)$, where $f(u,v,w)=(vw+wu+uv)/(u^2+v^2+w^2)$. The symbolic substitution $(a,b,c) \to (bc,ca,ab)$ maps the Yff conic of the symmedian point to that of the centroid. This mapping and others are used to find a large number of special points on many Yff conics.
Classification : 51M05
Mots-clés : Ellipse, hyperbola, parabola, symbolic substitution, triangle center, trilinear coordinates, trilinear product, Yff conic 
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     author = {C. Kimberling },
     title = {Yff {Conics}},
     journal = {Journal for geometry and graphics},
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     number = {1},
     year = {2008},
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}
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C. Kimberling . Yff Conics. Journal for geometry and graphics, Tome 12 (2008) no. 1, pp. 23-34. http://geodesic.mathdoc.fr/item/JGG_2008_12_1_JGG_2008_12_1_a2/