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First Fermat Point


OuterNapoleonsTheorem

The first Fermat point X (or F_1) (sometimes simply called "the Fermat point," Torricelli point, or first isogonic center) is the point X which minimizes the sum of distances from A, B, and C in an acute triangle,

 |AX|+|BX|+|CX|.
(1)

It has equivalent triangle center functions

alpha_(13)=csc(A+1/3pi)
(2)
alpha_(13)=bc[c^2a^2+(c^2+a^2-b^2)^2][a^2b^2-(a^2+b^2-c^2)^2][4Delta-sqrt(3)(b^2+c^2-a^2)]
(3)

and is Kimberling center X_(13) (Kimberling 1998, p. 67).

It also arises in Napoleon's theorem.


See also

Fermat Axis, Fermat Points, Napoleon's Theorem, Second Fermat Point

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References

Kazarinoff, N. D. Geometric Inequalities. New York: Random House, pp. 117-118, 1961.Kimberling, C. "Triangle Centers and Central Triangles." Congr. Numer. 129, 1-295, 1998.Kimberling, C. "Fermat Point." http://faculty.evansville.edu/ck6/tcenters/class/fermat.html.Kimberling, C. "Encyclopedia of Triangle Centers: X(13)=1st Isogonic Center." http://faculty.evansville.edu/ck6/encyclopedia/ETC.html#X13.

Referenced on Wolfram|Alpha

First Fermat Point

Cite this as:

Weisstein, Eric W. "First Fermat Point." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/FirstFermatPoint.html

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