J3 Triangular Cupola
A cupola is a polyhedron with two opposite polygons, of which one has twice as many vertices as the other and with alternating triangles and quadrangles as side faces. When all faces of the cupola are regular, then the cupola is a Johnson solid. There are three regular cupolae, the triangular (J3), the square (J4) and the pentagonal (J5) cupola.
The triangular cupola has 4 equilateral triangles, 3 squares, and a regular hexagon, for a total of 8 faces, 15 edges, and 9 vertices.
More information can be read here:
http://eusebeia.dyndns.org/4d/J3
https://polytope.miraheze.org/wiki/Triangular_cupola
You can download the Geogebra construction here: https://www.geogebra.org/m/x48ntrx4.
The triangular cupola has 4 equilateral triangles, 3 squares, and a regular hexagon, for a total of 8 faces, 15 edges, and 9 vertices.
More information can be read here:
http://eusebeia.dyndns.org/4d/J3
https://polytope.miraheze.org/wiki/Triangular_cupola
You can download the Geogebra construction here: https://www.geogebra.org/m/x48ntrx4.
Sample stereometry problem:
Prove that the angle 𝜃 between the planes (ABI) and (CDH) has cos(𝜃)=7/11.
Prove that the angle 𝜃 between the planes (ABI) and (CDH) has cos(𝜃)=7/11.
