The edge of a 3D shape is called an "edge." It is the line segment where two faces of the shape meet. In geometric terms, an edge is one of the fundamental components that define the structure of polyhedra and other solid figures.
edge
An edge.
A 3D semi circle
An impossible shape!
you call it a edge
CONE
Cylinder
A cone perhaps?
A cone.
it if called a edge for a 3D shape
2D shape = Decagon 3D shape = Decahedron
nonahedron