The first de Villiers point is the perspector of the reference triangle and its BCI
triangle, which is Kimberling center 
and has triangle
center function
The second de Villiers point is the perspector of the reference triangle and the excenter analog
of the BCI triangle, which is Kimberling center 
has triangle
center function
See also
BCI Triangle,
First de Villiers Point,
Perspector,
Second
de Villiers Point
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References
de Villiers, M. "A Dual to Kosnita's Theorem." Math. Info. Quart. 6, 169-171, 1996. http://mzone.mweb.co.za/residents/profmd/kosnita.htm.Referenced
on Wolfram|Alpha
de Villiers Points
Cite this as:
Weisstein, Eric W. "de Villiers Points."
From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/deVilliersPoints.html
Subject classifications
![alpha_(1128)=csc[1/4(pi+3A)]sin[1/4(pi-A)].](/images/equations/deVilliersPoints/NumberedEquation2.svg)
