#!/usr/bin/python

##file of sanjiaoxing mianji

import math

a = int(raw_input('please enter side a:')) b = int(raw_input('please enter side b:')) c = int(raw_input('please enter side c:')) if a + b <= c or b + c <= a or a + c <= b:         out = str(a)+','+str(b)+','+str(c)+" can't make a triangle" else:         p = (a + b + c )/2.0         s =math.sqrt(p * (p - a) * (p - b) * (p - c))         out = "the area of this trangle is%.2f " % s print out  

使用海伦公式,给初学者参考，我也是初学者......