The following pictures show n regular pentagons packed inside a unit circle, so that the total sum of the sides of the pentagons is as large as possible.
1.
2.
3.
Σ s = √((5–√5)/2) = 1.17557+
Trivial.
Σ s = 4√(1–2/√5) = 1.29968+
Trivial.
A continuum of solutions.
Σ s = 1.85411+
Found by Jonathan Viquerat
in June 2026.
4.
5.
6.
Σ s = 2.23179+
Found by Jonathan Viquerat
in June 2026.
Σ s = 2.51913+
Found by Jonathan Viquerat
in June 2026.
Σ s = 2.79197+
Found by Jonathan Viquerat
in June 2026.
7.
8.
9.
Σ s = 3.06697+
Found by Jonathan Viquerat
in June 2026.
Σ s = 3.31241+
Found by Jonathan Viquerat
in June 2026.
Σ s = 3.51482+
Found by Jonathan Viquerat
in June 2026.
10.
11.
12.
Σ s = 3.71141+
Found by Jonathan Viquerat
in June 2026.
Σ s = 3.91715+
Found by Jonathan Viquerat
in June 2026.
Σ s = 4.11652+
Found by Jonathan Viquerat
in June 2026.
13.
14.
15.
Σ s = 4.29822+
Found by Jonathan Viquerat
in June 2026.
Σ s = 4.49438+
Found by Haowei Lin
in June 2026.
Σ s = 4.65507+
Found by Haowei Lin
in June 2026.
16.
17.
18.
Σ s = 4.84434+
Found by Jonathan Viquerat
in June 2026.
Σ s = 5.00531+
Found by Jonathan Viquerat
in June 2026.
Σ s = 5.16108+
Found by Haowei Lin
in June 2026.
19.
20.
21.
Σ s = 5.31132+
Found by Haowei Lin
in June 2026.
Σ s = 5.45457+
Found by Haowei Lin
in June 2026.
Σ s = 5.58046+
Found by Haowei Lin
in June 2026.