from math import pi

class Sirkel:

    def __init__(self, r):
        self._radius = r

        
    def hentDiameter(self):
        diameter = 2*self._radius
        return diameter

    def omkrets(self):
        omkretsen = pi*self.hentDiameter()
        return omkretsen

    def areal(self):
        return pi*self._radius**2