Question

求Python大神帮助解答 貌似要写程序 关于三角函数面积

Part C - Area of a Triangle
Write a program that prompts the user for three side dimensions, as
floats, which then outputs the area of a triangle made up from these
three sides. The side dimensions, a, b and c, must not only be greater
than zero, but they must satisfy what is called the "Triangle
Inequality
Theorem" which is a fancy name for the rule that states: "The sum of two
sides must add up to be greater than the length of the remaining third
side." In terms of the side lengths, these statements must be
satisfied:
a + b > c
b + c > a
a + c > b
The area of any triangle
can be calculated using what is commonly called "Heron's Rule" after Heron
of Alexandria, even though the theorem was first developed by Archimedes.
Given the three sides, a, b and c:
s = (a + b + c)/2
area = sqrt(s(s - a)(s - b)(s - c))
Use the math.sqrt() function to calculate the square root. To use this function in the math module, you will need to place the statment import math at the top of your program before your def main() : line. Limit the output decimal places to two digits after the decimal point.

Answer 1

程序已经帮您写好，下面是按照要求的程序，因为没有说明如果构不成三角形应该输出什么，所以暂时先输出This is an invalid triangle这样的字样，如果有明确的要求，可以更改。
import math
a,b,c=raw_input("Please enter length of three sides: ").split()
a=float(a)
b=float(b)
c=float(c)
if a<=0 or b<=0 or c<=0:
print "This is an invalid triangle."
elif a+b<=c or a+c<=b or b+c<=a:
print "This is an invalid triangle."
else:
s=(a+b+c)/2
area=math.sqrt(s*(s-a)*(s-b)*(s-c))
print "%.2f" % area
经过一系列测试，这个程序是完全可行的，用的是Python 2.7.3

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Answer 2

import sys
import math
if len(sys.argv)<4:
print "you must input three side of a triangle"
sys.exit(-1)
try:
a,b,c=float(sys.argv[1]),float(sys.argv[2]),float(sys.argv[3])
if a+b>c and b+c>a and c+a>b and a>0 and b>0 and c>0:
s=(a+b+c)/2
area=math.sqrt(s*(s-a)*(s-b)*(s-c))
print "area is:",area
else:
print "the side can't match the rule"

except Exception as e:
print "we encount error:",e