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Bevan Point


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BevanPoint

The Bevan point V of a triangle DeltaABC is the circumcenter of the excentral triangle DeltaJ_AJ_BJ_C. It is named in honor of Benjamin Bevan, a relatively unknown Englishman proposed the problem of proving that the circumcenter O was the midpoint of the incenter I and the circumcenter of the excentral triangle and that the circumradius of the excentral triangle was 2R (Bevan 1806), a problem solved by John Butterworth (1806).

BevanPointIncenterCircumcenter
BevanPointNagelLongchamps
BevanPointSpiekerOrthocenter

V is the reflection of the incenter I in the circumcenter O (left figure), with

 IO=OV=sqrt(R^2-(abc)/(a+b+c)),
(1)

where R is the circumradius and a, b, and c are the side lengths of DeltaABC. It is also the midpoint of the line segment joining the Nagel point N and de Longchamps point L (middle figure), and the reflection of the orthocenter H in the Spieker center S (right figure). The corresponding squared distances are

NV^2=VL^2=3r^2+4R^2+4Rr-s^2
(2)
HS^2=SV^2=((r+4R)^2-3s^2)/4,
(3)

where r is the inradius and s is the semiperimeter (Queiroz Filho 2022).

The Bevan point is Kimberling center X_(40) and has triangle center function

 alpha_(40)=cosB+cosC-cosA-1.
(4)

It is the center of the Bevan circle and lies on the Darboux cubic.

BevanPointEulerLine

For O!=H, the Bevan point and incenter I are equidistant from the Euler line (P. Moses, pers. comm., Jan. 15, 2005). Their common distance is

 d=(|(a-b)(b-c)(c-a)|(a+b+c))/(8|OH|Delta),
(5)

where |OH| is the distance between the circumcenter and orthocenter, and Delta is the area of the reference triangle.


See also

Bevan Circle, Bevan's Theorem, Excentral Triangle

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References

Bevan, B. "VII. Question 67." In New Series of the Mathematical Repository, Vol. 1 (Ed. T. Leybourn). London, England: W. Glendenning, p. 18, 1806.Bogomolny, A. "Bevan's Point and Theorem." https://cut-the-knot.org/Curriculum/Geometry/BevanPoint.shtml.Butterworth, J. New Series of the Mathematical Repository, Vol. 1 (Ed. T. Leybourn). London, England: W. Glendenning, p. 143, 1806.Kimberling, C. "Triangle Centers and Central Triangles." Congr. Numer. 129, 1-295, 1998.Queiroz Filho, J. F. de. "The Bevan's Point and Its Special Relationships." Romanian Math. Mag. No. 1, 4-17, 2022.Wells, D. The Penguin Dictionary of Curious and Interesting Geometry. London, England: Penguin, p. 159, 1991.

Referenced on Wolfram|Alpha

Bevan Point

Cite this as:

Weisstein, Eric W. "Bevan Point." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/BevanPoint.html

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