has_facet_polytope rhombohedron
In Euclidean plane geometry , a ___MASK17___ is a quadrilateral with four right angles . It can also be defined as an equiangular quadrilateral , since equiangular means that all of its angles are equal ( 360 °/ 4 = 90 °). It can also be defined as a parallelogram containing a right angle . A ___MASK17___ with four sides of equal length is a ___MASK47___ . The term oblong is occasionally used to refer to a non - ___MASK47___ ___MASK17___ . A ___MASK17___ with vertices " ABCD " would be denoted as . In geometry , a ___MASK47___ is a regular quadrilateral , which means that it has four equal sides and four equal angles ( 90 - degree angles , or right angles ). It can also be defined as a rectangle in which two adjacent sides have equal length . A ___MASK47___ with vertices " ABCD " would be denoted . In geometry , a parallelepiped is a three - dimensional figure formed by six parallelograms ( the term rhomboid is also sometimes used with this meaning ). By analogy , it relates to a parallelogram just as a ___MASK41___ relates to a ___MASK47___ or as a cuboid to a rectangle . In Euclidean geometry , its definition encompasses all four concepts ( i . e ., " parallelepiped ", " parallelogram ", " ___MASK41___ ", and " ___MASK47___ "). In this context of affine geometry , in which angles are not differentiated , its definition admits only " parallelograms " and " parallelepipeds ". Three equivalent definitions of " parallelepiped " are The rectangular cuboid ( six rectangular faces ), ___MASK41___ ( six ___MASK47___ faces ), and the rhombohedron ( six ___MASK40___ faces ) are all specific cases of parallelepiped . In geometry , a rhombohedron is a three - dimensional figure like a ___MASK41___ , except that its faces are not squares but rhombi . It is a special case of a parallelepiped where all edges are the same length . It can be used to define the rhombohedral lattice system , a honeycomb with rhombohedral cells . In general the rhombohedron can have three types of rhombic faces in congruent opposite pairs , Ci symmetry , order 2 . Four points forming non - adjacent vertices of a rhombohedron necessarily form the four vertices of an orthocentric tetrahedron , and all orthocentric tetrahedra can be formed in this way . In Euclidean geometry , a ___MASK40___ () ( plural rhombi or rhombuses ) is a simple ( non - self - intersecting ) quadrilateral whose four sides all have the same length . Another name is equilateral quadrilateral , since equilateral means that all of its sides are equal in length . The ___MASK40___ is often called a diamond , after the diamonds suit in playing cards which resembles the projection of an octahedral diamond , or a lozenge , though the former sometimes refers specifically to a ___MASK40___ with a 60 ° angle ( see Polyiamond ), and the latter sometimes refers specifically to a ___MASK40___ with a 45 ° angle . In geometry , a ___MASK41___ is a three - dimensional solid object bounded by six ___MASK47___ faces , facets or sides , with three meeting at each vertex . In geometry , a cuboid is a convex polyhedron bounded by six quadrilateral faces , whose polyhedral graph is the same as that of a ___MASK41___ . While mathematical literature refers to any such polyhedron as a cuboid , other sources use " cuboid " to refer to a shape of this type in which each of the faces is a rectangle ( and 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 .