Answer
The cylinder is not a polyhedron because of its curved edge.
Work Step by Step
In geometry, a polyhedron may be defined as a figure solid in nature and surrounded by polygons. It consists of three dimensions with flat polygonal faces, edges,and vertices. A Pyramid and a rectangular solid may be considered as the examples of the polyhedron. The volume of a polyhedron is expressed in cubic units.
There are certain solid figures which are three-dimensional but are not polyhedrons. These figures include all those figures which have a curved or rounded edge such as a cylinder, sphere,and cone.
A polyhedron consists of vertices but owing to curved edges in the figures like a cylinder.Thus, these figures are not considered as the polyhedrons.