Triangular pyramid

The triangular pyramid, or tripy, is a type of tetrahedron with 1 equilateral triangle as a base and 3 isosceles triangles as sides. It is a pyramid based on the equilateral triangle.

It generally has 2 edge sizes, the base and side edges.

In vertex figures
Triangular pyramids occur as the vertex figures in 8 nonprismatic uniform polychora (including the truncated pentachoron, truncated tesseract, truncated icositetrachoron, truncated hecatonicosachoron, truncated great grand hecatonicosachoron, quasitruncated tesseract, quasitruncated small stellated hecatonicosachoron, and quasitruncated great grand stellated hecatonicosachoron) and 3 polyhedral prisms (the tetrahedral prism, dodecahedral prism, and great stellated dodecahedral prism).