# C. Ancient Berland Circus

# Nowadays all circuses in Berland have a round arena with diameter 13
# meters, but in the past things were different.
#
# In Ancient Berland arenas in circuses were shaped as a regular
# (equiangular) polygon, the size and the number of angles could vary
# from one circus to another. In each corner of the arena there was a
# special pillar, and the rope strung between the pillars marked the
# arena edges.
#
# Recently the scientists from Berland have discovered the remains of
# the ancient circus arena. They found only three pillars, the others
# were destroyed by the time.
#
# You are given the coordinates of these three pillars. Find out what
# is the smallest area that the arena could have.

import math

A = list(map(float, input().split()))
B = list(map(float, input().split()))
C = list(map(float, input().split()))



