input: Write a python function to calculate the area of a triangle using Heron's formula.
  assert Triangle(3, 4, 5).get_area() == 6.0
  assert Triangle(10, 10, 10).get_area() == 43.30127018922193
  assert Triangle(7, 24, 25).get_area() == 84.0
output: import math
  
  class Triangle:
      def __init__(self, a, b, c):
          self.a = a
          self.b = b
          self.c = c
  
      def get_area(self):
          s = (self.a + self.b + self.c) / 2
          area = math.sqrt(s * (s - self.a) * (s - self.b) * (s - self.c))
          return area