Pentagons have 5 sides and they can be regular or irregular
5 Shapes, 8 sides
They are the boundaries of the shapes.
Shapes that have four sides are known as quadrilaterals.
Pentagon (and in 3d: triangular prism and tetrahedron.)
Shapes with straight sides are called polygons
A square -- has 4 sides a triangle -- has 3 sides A pentagon -- has 5 sides A circle -- has one side