# File: peri.py
# Compute the perimeter of a triangle; user enters the points defining it
# WARNING: input is not error checked (see peri-c.py for how to do it right)
#
# Matt Bishop, ECS 10, Fall 2012
#
import math             # load up the math functions

#
# compute the distance between two points (ax, ay) and (bx, by)
#
def dist(ax, ay, bx, by):
    temp = (ax - bx) ** 2 + (ay - by) ** 2
    return math.sqrt(temp)

#
# compute the perimeter of the triangle defined by (ax, ay), (bx, by), (cx, cy)
#
def compperi(ax, ay, bx, by, cx, cy):
    d1 = dist(ax, ay, bx, by)
    d2 = dist(ax, ay, cx, cy)
    d3 = dist(bx, by, cx, cy)
    return d1 + d2 + d3

#
# construct the prompts
#
def prompt(xory, which):
    s = "Please enter the " + xory + " coordinate of the " + which + " point: "
    return s

#
################ MAIN PROGRAM
#

#
# read in the co-ordinates
#
try:
    iax = float(input(prompt("x", "first")))
    iay = float(input(prompt("y", "first")))
    ibx = float(input(prompt("x", "second")))
    iby = float(input(prompt("y", "second")))
    icx = float(input(prompt("x", "third")))
    icy = float(input(prompt("y", "third")))
except:
    print("All co-ordinates must be real numbers!")
else:
    #
    # print the corresponding triangle's perimeter
    #
    temp = compperi(iax, iay, ibx, iby, icx, icy)
    print("The perimeter is", temp)