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A space-filling tetrahedral disphenoid inside a cube. Two edges have dihedral angles of 90°, and four edges have dihedral angles of 60°. A disphenoid is a tetrahedron with four congruent triangles as faces; the triangles necessarily have all angles acute. The regular tetrahedron is a special case of a disphenoid.
Rarely, a right pyramid is defined to be a pyramid whose base is circumscribed about a circle and the altitude of the pyramid meets the base at the circle's center. [17] For the pyramid with an n-sided regular base, it has n + 1 vertices, n + 1 faces, and 2n edges. [18]
The solid angle of a four-sided right rectangular pyramid with apex angles a and b (dihedral angles measured to the opposite side faces of the pyramid) is = ( ()). If both the side lengths ( α and β ) of the base of the pyramid and the distance ( d ) from the center of the base rectangle to the apex of the pyramid (the center of ...
In geometry, the 5-cell is the convex 4-polytope with Schläfli symbol {3,3,3}. It is a 5-vertex four-dimensional object bounded by five tetrahedral cells. It is also known as a C 5, hypertetrahedron, pentachoron, [1] pentatope, pentahedroid, [2] tetrahedral pyramid, or 4-simplex (Coxeter's polytope), [3] the simplest possible convex 4-polytope, and is analogous to the tetrahedron in three ...
Square (regular quadrilateral): all four sides are of equal length (equilateral), and all four angles are right angles. An equivalent condition is that opposite sides are parallel (a square is a parallelogram), and that the diagonals perpendicularly bisect each other and are of equal length.
A square pyramid has five vertices, eight edges, and five faces. One face, called the base of the pyramid, is a square; the four other faces are triangles. [2] Four of the edges make up the square by connecting its four vertices. The other four edges are known as the lateral edges of the pyramid; they meet at the fifth vertex, called the apex. [3]
The lowest dimensional forms are 4 dimensional and connect two polygons. A p-q duopyramid or p-q fusil, represented by a composite Schläfli symbol {p} + {q}, and Coxeter-Dynkin diagram. The regular 16-cell can be seen as a 4-4 duopyramid or 4-4 fusil, , symmetry [[4,2,4]], order 128. A p-q duopyramid or p-q fusil has Coxeter group symmetry [p ...
2-dimensional hyperpyramid with a line segment as base 4-dimensional hyperpyramid with a cube as base. In geometry, a hyperpyramid is a generalisation of the normal pyramid to n dimensions. In the case of the pyramid one connects all vertices of the base (a polygon in a plane) to a point outside the plane, which is the peak. The pyramid's ...