# dist = math.sqrt(((x1-x2)**2) + ((y1-y2)**2))
# area_tri = 0.5*(a + b + c)

import math

def get_vertex():
	x = float(input("Enter x: "))
	y = float(input("Enter y: "))
	return x,y

def get_triangle():
	print("1st vertex")
	x1,y1 = get_vertex()
	print("2nd vertex")
	x2,y2 = get_vertex()
	print("3rd vertex")
	x3,y3 = get_vertex()
	return x1,y1,x2,y2,x3,y3

def side_length(x1,y1,x2,y2):
	return math.sqrt((x1-x2)**2 + (y1-y2)**2)

def calc_area(x1,y1,x2,y2,x3,y3):
	a = side_length(x1,y1,x2,y2)
	b = side_length(x2,y2,x3,y3)
	c = side_length(x3,y3,x1,y1)
	s = (1/2)*(a + b + c)
	return math.sqrt(s*(s-a)*(s-b)*(s-c))

# MAIN PROGRAM
x1,y1,x2,y2,x3,y3 = get_triangle()
area = calc_area(x1,y1,x2,y2,x3,y3)
print("Area is {:6.2f}".format(area))