//******************************************************************
// Triangle program
// This program exercises the IsTriangle function
//******************************************************************
#include <iostream>
#include <cmath>      // For fabs()

using namespace std;

bool IsTriangle( float, float, float );

int main()
{
    float angleA;    // Three potential angles of a triangle
    float angleB;
    float angleC;

    cout << "Enter 3 angles: ";
    cin >> angleA;
    while (cin)
    {
        cin >> angleB >> angleC;
        if (IsTriangle(angleA, angleB, angleC))
            cout << "The 3 angles form a valid triangle." << endl;
        else
            cout << "Those angles do not form a triangle." << endl;
        cout << "Enter 3 angles: ";
        cin >> angleA;
    }
    return 0;
}
  
//******************************************************************

bool IsTriangle( /* in */ float angle1,    // First angle
                 /* in */ float angle2,    // Second angle
                 /* in */ float angle3 )   // Third angle

// This function checks to see if its three incoming values
// add up to 180 degrees, forming a valid triangle

// Precondition:
//     angle1, angle2, and angle3 are assigned
// Postcondition:
//    Function value == true, if (angle1 + angle2 + angle3) is
//                            within 0.00000001 of 180.0 degrees
//                   == false, otherwise

{
    return (fabs(angle1 + angle2 + angle3 - 180.0) < 0.00000001);
}