'The inradius of the RegularPolygon.
The apothem/inradius is the radius of the inscribed circle.
Returns
apothem : number or instance of Basic
See Also
sympy.geometry.line.Segment.length, sympy.geometry.ellipse.Circle.radius
Examples
>>> from sympy import Symbol
>>> from sympy.geometry import RegularPolygon, Point
>>> radius = Symbol(\'r\')
>>> rp = RegularPolygon(Point(0, 0), radius, 4)
>>> rp.apothem
sqrt(2)*r/2'

@property
def apothem(self):

    return (self.radius * cos((S.Pi / self._n)))
