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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 2 n edges. [ 18 ]
The exterior face is a 60-90-30 triangle which is one-sixth of a tetrahedron face. The three faces interior to the tetrahedron are: a right triangle with edges , , , a right triangle with edges , , , and a right triangle with edges , , .
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 ...
If the legs have lengths a, b, c, then the trirectangular tetrahedron has the volume [2] =. The altitude h satisfies [3] = + +. The area of the base is given by [4] =. The solid angle at the right-angled vertex, from which the opposite face (the base) subtends an octant, has measure π /2 steradians, one eighth of the surface area of a unit sphere.
Some sources also require that each of the faces is a rectangle (so each pair of adjacent faces meets in a right angle). This more restrictive type of cuboid is also known as a rectangular cuboid, right cuboid, rectangular box, rectangular hexahedron, right rectangular prism, or rectangular parallelepiped. [5] Polyhedron
Right-rectangular pyramid: a, b = the sides of the base h = the distance is from base to the apex General triangular prism: b = the base side of the prism's ...
The height of a right square pyramid can be similarly obtained, with a substitution of the slant height formula giving: [6] = =. A polyhedron 's surface area is the sum of the areas of its faces. The surface area A {\displaystyle A} of a right square pyramid can be expressed as A = 4 T + S {\displaystyle A=4T+S} , where T {\displaystyle T} and ...
The restriction m ≥ 3 enforces that the polygonal faces must have at least three sides. When considering polyhedra as a spherical tiling, this restriction may be relaxed, since digons (2-gons) can be represented as spherical lunes, having non-zero area. Allowing m = 2 admits a new infinite class of regular polyhedra, which are the hosohedra.