float alfa (float x, float y) {
  
  float a = 46.3;
  float b = 73.5;
  
  float cosalfa = (sq(a)+sq(x)+sq(y)-sq(b))/(2*a*sqrt(sq(x)+sq(y)));
  float alfa = -atan(-cosalfa/sqrt(1-sq(cosalfa))) - atan(y/x) -PI/4;
  
  return (alfa);
  
}
  
  
float beta (float x, float y) {
  
  float a = 46.3;
  float b = 73.5;
  
  float cosbeta = (sq(a)+sq(b)-sq(x)-sq(y))/(2*a*b);
  float beta = -atan(-cosbeta/sqrt(1-sq(cosbeta)));
  
  return (beta);
  
}