Because that is how a polyhedron is defined.
Because that is how a polyhedron is defined.
Because that is how a polyhedron is defined.
312
A polyhedron.
It is so by definition.
A paraboloid.
A polyhedron is a three-dimensional solid with flat faces, straight edges, and sharp corners, while a non-polyhedron does not have these characteristics. Polyhedra are made up of polygons that enclose a single region of space, while non-polyhedra may have curved faces or intersecting edges. In mathematical terms, a polyhedron satisfies Euler's formula (V - E + F = 2), where V is the number of vertices, E is the number of edges, and F is the number of faces, while a non-polyhedron does not.
Cylinder - a solid figure formed by two congruent parallel circles joined by a curved surface.
Sphere
cube
A semicircle
A figure with 2 circular bases and one curved surface is called a cylinder. Examples are food cans.