User Grigory M - Mathematics Stack Exchange

40 votes

4 answers

14k views

Dividing an equilateral triangle into N equal (possibly non-connected) parts

asked Jun 24, 2016 at 21:20

30 votes

5 answers

7k views

Ramanujan-type trigonometric identities with cube roots, generalizing $\sqrt[3]{\cos(2\pi/7)}+\sqrt[3]{\cos(4\pi/7)}+\sqrt[3]{\cos(8\pi/7)}$

asked Jan 19, 2014 at 18:22

26 votes

2 answers

3k views

Strehl identity for the sum of cubes of binomial coefficients

asked Nov 29, 2013 at 21:46

25 votes

2 answers

1k views

Spherical cap area is $\pi r^2$. But why?

asked Nov 5, 2021 at 17:23

24 votes

2 answers

8k views

Probability that the convex hull of random points contains sphere's center

asked Aug 2, 2010 at 13:59

23 votes

7 answers

4k views

Why $PSL_3(\mathbb F_2)\cong PSL_2(\mathbb F_7)$?

asked Aug 2, 2010 at 14:19

20 votes

4 answers

3k views

Explicit formula for Fermat's 4k+1 theorem

asked Oct 19, 2011 at 21:31

14 votes

2 answers

2k views

Law of sines: uniform proof of Euclidean, spherical & hyperbolic cases

asked Dec 13, 2014 at 23:20

12 votes

1 answer

1k views

Counting subsets with r mod 5 elements

asked Aug 2, 2010 at 10:41

12 votes

1 answer

8k views

Geometric Proof of the Formula for Simplex Numbers

asked Aug 14, 2010 at 11:22

10 votes

3 answers

730 views

Direct proof of Gelfand-Zetlin identity

asked Aug 5, 2010 at 20:18

9 votes

2 answers

461 views

Path-type description for (faces of) associahedra?

asked Aug 13, 2011 at 16:04

9 votes

1 answer

414 views

When do 10 points lie on a cubic? (a la Pascal)

asked Oct 18, 2017 at 22:35

6 votes

1 answer

949 views

Gauss-type sums for cube roots

asked Jan 26, 2012 at 20:04

6 votes

1 answer

267 views

Why does «Massey cube» of an odd element lie in 3-torsion?

asked Jun 26, 2013 at 13:19

5 votes

1 answer

441 views

Recurrence $(n+2)\text{Cat}_{n+1}=(4n+2)\text{Cat}_n$ for non-crossing matchings

asked Jan 1, 2014 at 17:52

4 votes

1 answer

658 views

Octonionic Hopf fibration and $\mathbb HP^3$

asked Apr 26, 2011 at 13:15

4 votes

0 answers

412 views

Counter-example to exponential law for locally compact [non-Hausdorff] spaces [duplicate]

asked Mar 30, 2015 at 15:27

3 votes

1 answer

908 views

Cohomology rings of (some) sphere bundles over spheres

asked May 29, 2011 at 15:28

2 votes

1 answer

306 views

What is $\mathbb C[a_1,a_2,a_3,\dots]/a(t)^2$ (where $a(t)$ is $a_1t+a_2t^2+\dots$)?

asked Jun 29, 2011 at 10:15

2 votes

1 answer

449 views

Gauss sum in regular 7-gon

asked Jan 20, 2018 at 19:54

1 vote

2 answers

1k views

Combinatorial definition of Hall–Littlewood polynomials (sum over SSYT?)

asked Dec 27, 2014 at 19:36

Stack Exchange Network

22 Questions

Dividing an equilateral triangle into N equal (possibly non-connected) parts

Ramanujan-type trigonometric identities with cube roots, generalizing $\sqrt[3]{\cos(2\pi/7)}+\sqrt[3]{\cos(4\pi/7)}+\sqrt[3]{\cos(8\pi/7)}$

Strehl identity for the sum of cubes of binomial coefficients

Spherical cap area is $\pi r^2$. But why?

Probability that the convex hull of random points contains sphere's center

Why $PSL_3(\mathbb F_2)\cong PSL_2(\mathbb F_7)$?

Explicit formula for Fermat's 4k+1 theorem

Law of sines: uniform proof of Euclidean, spherical & hyperbolic cases

Counting subsets with r mod 5 elements

Geometric Proof of the Formula for Simplex Numbers

Direct proof of Gelfand-Zetlin identity

Path-type description for (faces of) associahedra?

When do 10 points lie on a cubic? (a la Pascal)

Gauss-type sums for cube roots

Why does «Massey cube» of an odd element lie in 3-torsion?

Recurrence $(n+2)\text{Cat}_{n+1}=(4n+2)\text{Cat}_n$ for non-crossing matchings

Octonionic Hopf fibration and $\mathbb HP^3$

Counter-example to exponential law for locally compact [non-Hausdorff] spaces [duplicate]

Cohomology rings of (some) sphere bundles over spheres

What is $\mathbb C[a_1,a_2,a_3,\dots]/a(t)^2$ (where $a(t)$ is $a_1t+a_2t^2+\dots$)?

Gauss sum in regular 7-gon

Combinatorial definition of Hall–Littlewood polynomials (sum over SSYT?)