No triangle can be cut into seven congruent triangles
arXiv:1811.09723
Abstract
We prove the theorem in the title, and prove the theorem for 11 as well as 7. By previous work of others, the problem reduces to a number of cases. The cases not solved already are solved here.
39 pages, 26 figures. The treatment of isosceles triangles has been replaced by a citation of the paper Tilings of an Isosceles Triangle, which seems a better organization of the material and reduces the length of this paper. arXiv admin note: text overlap with arXiv:1206.1974