#include <cmath>

void triangle_area(double a,double b,double c,double &area,double &perimeter){
  double s, asq;

  if ( a <= 0 || b <= 0 || c <= 0 ) {
    area = 0.0;
    perimeter = 0.0;
    return;
  }
  perimeter = a + b + c;
  s = perimeter/2.0;
  asq = s* (s-a) *(s-b)*(s-c);
  if ( asq <= 0 ) {
    area = 0.0;
    perimeter = 0.0;
    return;
  }
  area = sqrt(asq);
  return;
}