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  2. Cylinder - Wikipedia

    en.wikipedia.org/wiki/Cylinder

    The bare term cylinder often refers to a solid cylinder with circular ends perpendicular to the axis, that is, a right circular cylinder, as shown in the figure. The cylindrical surface without the ends is called an open cylinder. The formulae for the surface area and the volume of a right circular cylinder have been known from early antiquity.

  3. Platonic solid - Wikipedia

    en.wikipedia.org/wiki/Platonic_solid

    In geometry, a Platonic solid is a convex, regular polyhedron in three-dimensional Euclidean space.Being a regular polyhedron means that the faces are congruent (identical in shape and size) regular polygons (all angles congruent and all edges congruent), and the same number of faces meet at each vertex.

  4. Solid geometry - Wikipedia

    en.wikipedia.org/wiki/Solid_geometry

    A parallelepiped where all edges are the same length; A cube, except that its faces are not squares but rhombi; Cuboid: A convex polyhedron bounded by six quadrilateral faces, whose polyhedral graph is the same as that of a cube [4] Some sources also require that each of the faces is a rectangle (so each pair of adjacent faces meets in a right ...

  5. Euler characteristic - Wikipedia

    en.wikipedia.org/wiki/Euler_characteristic

    In mathematics, and more specifically in algebraic topology and polyhedral combinatorics, the Euler characteristic (or Euler number, or Euler–Poincaré characteristic) is a topological invariant, a number that describes a topological space's shape or structure regardless of the way it is bent.

  6. Steinmetz solid - Wikipedia

    en.wikipedia.org/wiki/Steinmetz_solid

    The generation of a bicylinder Calculating the volume of a bicylinder. A bicylinder generated by two cylinders with radius r has the volume =, and the surface area [1] [6] =.. The upper half of a bicylinder is the square case of a domical vault, a dome-shaped solid based on any convex polygon whose cross-sections are similar copies of the polygon, and analogous formulas calculating the volume ...

  7. Right circular cylinder - Wikipedia

    en.wikipedia.org/wiki/Right_circular_cylinder

    A right circular cylinder is a cylinder whose generatrices are perpendicular to the bases. Thus, in a right circular cylinder, the generatrix and the height have the same measurements. [ 1 ] It is also less often called a cylinder of revolution, because it can be obtained by rotating a rectangle of sides r {\displaystyle r} and g {\displaystyle ...

  8. Duocylinder - Wikipedia

    en.wikipedia.org/wiki/Duocylinder

    The duocylinder is bounded by two mutually perpendicular 3-manifolds with torus-like surfaces, respectively described by the formulae: + =, + and + =, + The duocylinder is so called because these two bounding 3-manifolds may be thought of as 3-dimensional cylinders 'bent around' in 4-dimensional space such that they form closed loops in the xy - and zw-planes.

  9. Regular polyhedron - Wikipedia

    en.wikipedia.org/wiki/Regular_polyhedron

    A regular polyhedron is identified by its Schläfli symbol of the form {n, m}, where n is the number of sides of each face and m the number of faces meeting at each vertex. There are 5 finite convex regular polyhedra (the Platonic solids ), and four regular star polyhedra (the Kepler–Poinsot polyhedra ), making nine regular polyhedra in all.