Basic triangle program
hi guys,
please I have created just very basic program that decides if it is triangle or not, If yes it counts S. But somehow when I write sides 1.1 2.2 3.3 // It does not show"not triangel"For other values it works but not for these . Can you tell me why? Thanks.
#include <iostream>
#include <cmath>
using namespace std;
int main()
{
cout <<"Write sides of triangle a, b, c:"<<endl;
double a, b, c;
double s,S;
cin >>a>>b>>c;
if((a+b)<=c || (b+c)<=a || (c+a)<=b || cin.fail() || a <= 0 || b <= 0 || c <= 0 )
cout <<"Not triangel."<< endl;
else
{
s = (a + b + c) / 2;
S = sqrt(s * (s - a) * (s - b) * (s - c));
cout <<"S triangle is "<<S<<endl;
}
return 0;
}
please I have created just very basic program that decides if it is triangle or not, If yes it counts S. But somehow when I write sides 1.1 2.2 3.3 // It does not show"not triangel"For other values it works but not for these . Can you tell me why? Thanks.
#include <iostream>
#include <cmath>
using namespace std;
int main()
{
cout <<"Write sides of triangle a, b, c:"<<endl;
double a, b, c;
double s,S;
cin >>a>>b>>c;
if((a+b)<=c || (b+c)<=a || (c+a)<=b || cin.fail() || a <= 0 || b <= 0 || c <= 0 )
cout <<"Not triangel."<< endl;
else
{
s = (a + b + c) / 2;
S = sqrt(s * (s - a) * (s - b) * (s - c));
cout <<"S triangle is "<<S<<endl;
}
return 0;
}
closed account (48T7M4Gy)
The triangle inequality is based on the sum of two sides being greater than the third side, not greater than or equal, which is a straight line ( or a degenerate triangle with zero area if you prefer).
https://en.wikipedia.org/wiki/Triangle_inequality
https://en.wikipedia.org/wiki/Triangle_inequality
Last edited on
| The triangle inequality is base on the sum of two sides being greater than the third side |
But that's what the OP's code does. If the sum of any two sides is <= the third side, then he says it's not a triangle.
The problem is that lengths 1.1, 2.2 and 3.3 exactly form a line but these base 10 numbers can't be exactly represented in the base 2 floating point format used by your computer.
BTW, for this reason, most scientific calculators use base 10, even though it's slower to do the calculations.
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