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Desmic Mate


Let DeltaA^'B^'C^' be a triangle perspective to a reference triangle DeltaABC with perspector D^('').

Let A^('') be the intersection of lines BC^' and CB^', B^('') the intersection of AC^' and CA^', and C^('') the intersection of AB^' and BA^'. Then A^('')B^('')C^('') is called the desmic mate of A^'B^'C^'.

The desmic mate is perspective to both ABC through a point D^' and to A^'B^'C^' through a point D, and the perspectors are collinear. The twelve points are all perspectors of the two quadrangles (ABCD, A^'B^'C^'D^', A^('')B^('')C^('')D^('')) of which they are not a vertex and can be viewed as the projection to the plane of a desmic configuration.

The triangles ABC, A^'B^'C^' and its desmic mate have a common perspectrix. The trilinear pole of this perspectrix lies on the line DD^'D^(''), more precisely it is the harmonic conjugate of D w.r.t. D^' and D^('') (van Lamoen 1999).

The pairs (A^',A^('')), (B^',B^('')), (C^',C^('')) and (D^',D^('')) are pairs of the same isoconjugation.

The twelve points A, B, C, D, A^', B^', C^', D^', A^(''), B^(''), C^(''), D^('') lie on an isocubic (Dean and van Lamoen 2001) with pivot point D.


See also

Desmic Configuration, Perspectrix, Perspector

This entry contributed by Floor van Lamoen

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References

Dean, K. R. and van Lamoen, F. M. "Geometric Construction of Reciprocal Conjugates." Forum Geom. 1, 115-120, 2001. http://forumgeom.fau.edu/FG2001volume1/FG200116index.html.van Lamoen, F. M. "Bicentric Triangles." Nieuw Arch. Wisk. 17, 363-372, 1999.

Referenced on Wolfram|Alpha

Desmic Mate

Cite this as:

van Lamoen, Floor. "Desmic Mate." From MathWorld--A Wolfram Web Resource, created by Eric W. Weisstein. https://mathworld.wolfram.com/DesmicMate.html

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