RegularPolygon
RegularPolygon[n] gives the regular polygon with n vertices equally spaced around the unit circle.
RegularPolygon[r,n] gives the regular polygon of radius r.
RegularPolygon[{r,θ},n] starts at angle θ with respect to the x axis.
RegularPolygon[{x,y},rspec,n] centers the polygon at {x,y}.
Please visit the official Wolfram Language Reference for more details and examples on core symbols.