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Outer García Triangle


OuterGarciaTriangle

The outer García triangle of a nondegenerate reference triangle ABC is the triangle A_tB_tC_t obtained by reflecting its incenter I in the three side midpoints. In radius vectors,

A_t=B+C-I
(1)
B_t=C+A-I
(2)
C_t=A+B-I.
(3)

This is the half-turn image of the reference triangle about the Spieker center, so it is congruent to ABC (García 2014, Dalcín and Kiss 2021).

Reflecting its vertices across the corresponding sidelines of ABC gives the inner García triangle (García 2014).

Its vertex A_t is the orthocenter of BCI_a, where I_a is the excenter opposite A, and the other two vertices are obtained cyclically (Dalcín and Kiss 2021). Its orthocenter is the Bevan point 2O-I, where O is the circumcenter of ABC (Dalcín and Kiss 2021).

The outer García triangle is perspective to the García reflection triangle at the Nagel point (Dalcín and Kiss 2021).


See also

García Reflection Triangle, Incenter, Inner García Triangle, Reflection, Reflection Triangle, Spieker Center

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References

Dalcín, M. and Kiss, S. N. "Some Properties of the García Reflection Triangles." J. Geom. Graphics 25, 119-126, 2021. https://www.heldermann-verlag.de/jgg/jgg25/j25h1dalc.pdf.García, E. A. J. "A Note on Reflections." Forum Geom. 14, 155-161, 2014. https://drive.google.com/file/d/1HgLcT5S9immBULeiMr1IqPHbSCY4OTdo/view.

Cite this as:

Weisstein, Eric W. "Outer García Triangle." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/OuterGarciaTriangle.html

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