Yes
It is a circumcircle or circumscribing circle.
all sides are the same
apolygon is a shape that has no curves ,is closed, and has more then three sides
A polygon with 11 sides is called an "undecagon."
6 sides
A trapezoid
The number of sides and vertices are the same
A two dimensional shape with 3 sides or more is considered to be a polygon
3, otherwise below that it just collapses to a straight line or even a point.
False. It could be an irregular pentagon.
If by cube you mean perfect cube (a cube of an integer), then no, and the nearest perfect cube is 81.