c Program to Find Area of a Triangle using Hero’s Formula

// Program to Find Area of a Triangle using Hero’s Formula
#include <stdio.h>
#include <math.h>
main()
{
float a, b, c, s, area;
back:
printf("\nEnter three sides of a triangle: ");
scanf("%f %f %f", &a, &b, &c);
if (a==0 || b==0 || c==0)
{
printf("\nValue of any side should not be equal to
zero\n");
goto back;
}
if (a+b<c || b+c<a || c+a<b)
{
printf("\nSum of two sides should not be less than
third\n");
goto back;
}
s = (a + b + c) / 2;
area = sqrt(s * (s - a) * (s - b) * (s - c));
printf("\n\nArea of triangle: %.2f", area);
getch();
}


A formula for calcualting the area of a triangle when all sides are known is attirbuted to Heron of Alexandria but it is thought to be the work of Archimedes. At any rate, the formula is as follows:
A triangle has sides a, b, and c.
After Calculating S, where S = (a+b+c)/2
The Area of a Triangle = SQRT(s*(s-a)(s-b)(s-c))