- Romania is a country at the crossroads of Central, Eastern and Southeastern Europe. It borders Ukraine to the north and east, Hungary to the west, Serbia to the southwest, Bulgaria to the south, Moldova to the east, and the Black Sea to the southeast. It has a predominantly continental climate, and an area of 238,397 km2 (92,046 sq mi) with a population of 19 million people (2023). Romania is the twelfth-largest country in Europe and the sixth-most populous member state of the European Union. Its capital and largest city is Bucharest, followed by Cluj-Napoca, Iași, Timișoara, Constanța, Craiova, Brașov, and Galați.
- Regular tetrahedron (Wikipedia)
A regular tetrahedron is a tetrahedron in which all four faces are equilateral triangles. In other words, all of its faces are the same size and shape (congruent) and all edges are the same length. A convex polyhedron in which all of its faces are equilateral triangles is the deltahedron. There are eight convex deltahedra, one of which is the regular tetrahedron.
