L shape
An incomplete shape.
cone
triangle
A cone has one vertex, one edge, and one base.
A cone would fit the given description.
L shape
It could be a pyramid shape
A diagonal in a shape is a straight line from one vertex to another vertex (corner).
A cone has one vertex and one edge.
A pyramid with an irregular pentagon base.
An incomplete shape.
cone
triangle
A cone has one vertex, one edge, and one base.
polyhedra
A cone.