Triangles in Circles

The following pictures show n equilateral triangles packed inside a unit circle, so that the total sum of the sides of the triangles is as large as possible.


1.
           2.
           3.
Σ s = √3 = 1.73205+
Trivial.
 
Σ s = 4/√3 = 2.30940+
Trivial.
A continuum of solutions.
Σ s = 3.18767+
Found by Jonathan Viquerat
in June 2026.


4.
           5.
           6.
Σ s = 3+2/√3 = 4.15470+
Found by Jonathan Viquerat
in June 2026.
Σ s = 5
Trivial.
 
Σ s = 6
Trivial.
 


7.
           8.
           9.
Σ s = 5+2/√3 = 6.15470+
Found by Jonathan Viquerat
in June 2026.
Σ s = 6.62452+
Found by Jonathan Viquerat
in June 2026.
Σ s = 7.00636+
Found by Haowei Lin
in July 2026.


10.
           11.
           12.
Σ s = 7.39853+
Found by Jonathan Viquerat
in June 2026.
Σ s = 7.77426+
Found by Jonathan Viquerat
in June 2026.
Σ s = 8.09500+
Found by Jonathan Viquerat
in June 2026.


13.
           14.
           15.
Σ s = 8.53190+
Found by Jonathan Viquerat
in June 2026.
Σ s = 8.83315+
Found by Jonathan Viquerat
in June 2026.
Σ s = 9.25219+
Found by Jonathan Viquerat
in June 2026.


16.
           17.
           18.
Σ s = 9.57822+
Found by Jonathan Viquerat
in June 2026.
Σ s = 9.93206+
Found by Jonathan Viquerat
in June 2026.
Σ s = 10.23593+
Found by Pedro Martins
in October 2026.


19.
           20.
           21.
Σ s = 10.55252+
Found by Pedro Martins
in October 2026.
Σ s = 10.86683+
Found by Jonathan Viquerat
in June 2026.
Σ s = 11.16682+
Found by Jonathan Viquerat
in September 2026.


22.
           23.
           24.
Σ s = 11.44937+
Found by Joost de Winter
in October 2026.
Σ s = 11.73932+
Found by Jonathan Viquerat
in September 2026.
Σ s = 12
Found by Joost de Winter
in September 2026.


25.
           26.
           27.
Σ s = 12.26626+
Found by Joost de Winter
in October 2026.
Σ s = 12.58697+
Found by Joost de Winter
in October 2026.
Σ s = 12.82835+
Found by Joost de Winter
in October 2026.


28.
           29.
           30.
Σ s = 13.12517+
Found by Pedro Martins
in October 2026.
Σ s = 13.33763+
Found by Pedro Martins
in October 2026.
Σ s = 13.60246+
Found by Pedro Martins
in October 2026.


31.
           32.
           33.
Σ s = 13.86560+
Found by Joost de Winter
in October 2026.
Σ s = 14.12516+
Found by Pedro Martins
in October 2026.
Σ s = 14.36499+
Found by Pedro Martins
in October 2026.


34.
           35.
           36.
Σ s = 14.57958+
Found by Pedro Martins
in October 2026.
Σ s = 14.84016+
Found by Pedro Martins
in October 2026.
Σ s = 15.05771+
Found by Joost de Winter
in October 2026.


37.
           38.
           39.
Σ s = 15.30332+
Found by Joost de Winter
in October 2026.
Σ s = 15.50947+
Found by Joost de Winter
in October 2026.
Σ s = 15.74485+
Found by Joost de Winter
in October 2026.


40.
           41.
           42.
Σ s = 15.94371+
Found by Pedro Martins
in October 2026.
Σ s = 16.17076+
Found by Pedro Martins
in October 2026.
Σ s = 16.37290+
Found by Pedro Martins
in October 2026.


43.
           44.
           45.
Σ s = 16.60547+
Found by Pedro Martins
in October 2026.
Σ s = 16.79364+
Found by Joost de Winter
in October 2026.
Σ s = 17.02613+
Found by Joost de Winter
in October 2026.


46.
           47.
           48.
Σ s = 17.20351+
Found by Pedro Martins
in October 2026.
Σ s = 17.43024+
Found by Joost de Winter
in October 2026.
Σ s = 17.59270+
Found by Pedro Martins
in October 2026.


49.
           50.
Σ s = 17.78684+
Found by Pedro Martins
in October 2026.
Σ s = 17.99127+
Found by Pedro Martins
in October 2026.