Octogon. Eight sides, think of OCTOpus which has eight legs.
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Reuleaux triangle
It is a regular 8 sided octagon.
The shape has 50 sides is Pentacontagon
There is no specific name for such a shape.
octagon
An 8 sided octagon would fit the given description.
A shape with eight straight sides is called on octagon. There is not another specific name, but you could call it the more generic name: polygon.
Octogon. Eight sides, think of OCTOpus which has eight legs.
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quadrilateral shape
Reuleaux triangle
It is a regular 8 sided octagon.
An Octogon An Octogon regular regular
The shape has 50 sides is Pentacontagon
A shape with six sides is a hexagon.