def get_area(self):
        """
        Calculates shape's area.

        Returns:
            float: area of the shape
        """

        if self.shape == "Circle":
            self.area = math.pi * self.r ** 2
        elif self.shape == "Triangle" or self.shape == "Equilateral Triangle":
            self.area = math.sqrt(self.s*(self.s-self.a)*(self.s-self.b)*(self.s-self.c))
        elif self.shape == "Rectangle" or self.shape == "Square":
            self.area = self.a * self.b
        elif self.shape == "Regular Pentagon":
            self.area = self.a**2 * math.sqrt(5*(5+2*math.sqrt(5)))/4

        return self.area