The name of the shape is a quadrilateral.
It is usually a regular polygon that has equal sides.
Square. By definition, its sides must all be equal.
icosahedron (solid shape) icosagon (2 dimensional) See related link.
Reuleaux triangle
A two-dimensional shape with three sides is a triangle. A three-dimensional shape with three faces is a cylinder.
A shape that has 10 sides (two dimensional) is called a decagon. A shape that has 10 faces (three dimensional) is call a decahedron.
A cube...
The name of the shape is a quadrilateral.
It is usually a regular polygon that has equal sides.
Square. By definition, its sides must all be equal.
Hexagon
A polygon is a 2 dimensional shape with 3 or more sides.
icosahedron (solid shape) icosagon (2 dimensional) See related link.
irregular
Square
Pentagon