Определить углы треугольника используя вектора на плоскости

#include <iostream>
#include <cmath>
 
using namespace std;
 
int main ()
{
  int A1, A2;
  int B1, B2;
  int C1, C2;
  
  cout << "A1, A2 :" << endl;
  cin >> A1 >> A2;
  
  cout << "B1, B2 :" << endl;
  cin >> B1 >> B2;
  
  cout << "C1, C2 :" << endl;
  cin >> C1 >> C2;
  
  int AB1 = B1 - A1;
  int AB2 = B2 - A2;
  
  int AC1 = C1 - A1;
  int AC2 = C2 - A2;
  
  double AB = sqrt (AB1 * AB1 + AB2 * AB2);
  
  double AC = sqrt (AC1 * AC1 + AC2 * AC2);
  
  double cosA = (AB1 * AC1 + AB2 * AC2) / (AB * AC);
  
  int angA;
  
  if (cosA == 0)
    {
      angA = 90;
    }
  else
    {
      cout << "cosA = " << cosA << endl;
      
      cout << "angA :" << endl;
      cin >> angA;
    }
  int BA1 = A1 - B1;
  int BA2 = A2 - B2;
  
  int BC1 = C1 - B1;
  int BC2 = C2 - B2;
  
  double BA = AB;
  
  double BC = sqrt (BC1 * BC1 + BC2 * BC2);
  
  double cosB = (BA1 * BC1 + BA2 * BC2) / (BA * BC);
  
  int angB;
 
  if (cosB == 0)
    {
      angB = 90;
    }
  else
    {
      cout << "cosB = " << cosB << endl;
      
      cout << "angB :" << endl;
      cin >> angB;
    }
  int angC = 180 - (angA + angB);
  
  cout << "angA = " << angA << endl;
  cout << "angB = " << angB << endl;
  cout << "angC = " << angC << endl;
}