hendecagon
A quadrilateral is a closed plane figure with four straight sides.
An 8-sided plane figure is an octagon.
A expample of a plane figure with 6 sides and 6 vertices is called a hexagon. hex means 6.
It is a dodecagon
A hendecagon.
hendecagon
An 11-sided figure is a hendecagon, or an undecagon. Either name applies.
A plane figure with eight sides is an octagon.
A quadrilateral is a closed plane figure with four straight sides.
If they are straight sides, then a polygon. Otherwise, simply "a closed plane figure with 3 or more sides".
its self because a plane figure is a figure that is flat and has all strait sides.
An 8-sided plane figure is an octagon.
circle
No plane figure has four vertices unless it has four sides.
hendecagon
None. A figure must have more sides than angles.