The scope of this collection

Elementary Geometry is a growing collection of problems, proofs, and diagrams. Its central concern is the structure of classical Euclidean geometry: how a configuration becomes intelligible through a well-chosen construction, transformation, or invariant.

The collection favours concise arguments that can be reused, alternative proofs that reveal different features of a figure, and diagrams precise enough to support the mathematics rather than merely decorate it.

English is the primary language of the site. Japanese versions may be added under/ja/ after separate mathematical and editorial review. A translation link is shown only when a reviewed counterpart exists.

1. 01

   Public pages distinguish statements, observations, proofs, and interpretations.

2. 02

   Sources and publication status are recorded without guessing missing bibliographic data.

3. 03

   Unpublished original work and private drafts are not placed in the public repository.