using System;class Program { static void Main(string[] args) { double a, b, c, p, s; a = Convert.ToDouble(Console.ReadLine()); b = Convert.ToDouble(Console.ReadLine()); c = Convert.ToDouble(Console.ReadLine()); p = (a + b + c) / 2; s = p * (p - a) * (p - b) * (p - c); if (a <= 0 || b <= 0 || c <= 0 || s <= 0) Console.WriteLine("不能构成三角形"); else Console.WriteLine("面积={0}", Math.Sqrt(s)); } }
任意两边之差小于第三边;已知三角形三边a,b,c,则 (海伦公式)(p=(a+b+c)/2)
S=√[p(p-a)(p-b)(p-c)] =(1/4)√[(a+b+c)(a+b-c)(a+c-b)(b+c-a)]
{
static void Main(string[] args)
{
double a, b, c, p, s;
a = Convert.ToDouble(Console.ReadLine());
b = Convert.ToDouble(Console.ReadLine());
c = Convert.ToDouble(Console.ReadLine());
p = (a + b + c) / 2;
s = p * (p - a) * (p - b) * (p - c);
if (a <= 0 || b <= 0 || c <= 0 || s <= 0)
Console.WriteLine("不能构成三角形");
else
Console.WriteLine("面积={0}", Math.Sqrt(s));
}
}