🚀 go-pugleaf

hi...im working with jbuilder and i have a problem with Math class.... i write my class but in the teta2 angle send me an NaN i was checking but i cant found the problem... somebody can help me??? is urgent..this is my class


import java.math.*;
import java.util.*;
import java.lang.*;
import java.text.*;

public class Cinversa {

 public Cinversa(String coordx,String coordy) {
   double B;
   double x,y;
   double r;

    double r2, x2, y2, teta1, teta2, L1, L2, t, L12, L22;
    double Beta, Gama, G, fi, fi2, rad1, rad2;
int largo;

 String X3 =coordx;
 String Y3 = coordy;

     x = Double.valueOf(coordx).doubleValue();
     y = Double.valueOf(coordy).doubleValue();


    if (y != 0) {
  L1 = 62.5;
  L2 = 53;
  System.out.println(x);
  System.out.println(y);
  x2 = Math.pow(x,2);
  y2 = Math.pow(y,2);
  r2 = (x2+y2);
  r = Math.sqrt(r2);
  System.out.println(r2);

  G = (r2 + Math.pow(L1,2) - Math.pow(L2,2))/(2*L1*r);
  System.out.println(G);
  Gama = Math.acos(G);
  System.out.println("gama");
  B = y/x;
  System.out.println(B);
  Beta = Math.atan(B);
  System.out.println(Beta);


  fi = (r2 - Math.pow(L1,2) - Math.pow(L2,2))/(2*L1*L2);
  System.out.println(fi);
    System.out.println("fi");
 teta2 = Math.acos(fi);*******here is the problem***********
        System.out.println(teta2);
    System.out.println("teta2");


     if (teta2 > 0) {

       teta1 = (Beta - Gama);
        t = (teta1 *625)/1450;
        System.out.println(teta1);
      }

     if (teta2 < 0) {

       teta1 = (Beta + Gama);
        t = (teta1 *625)/1450;
        System.out.println(teta1);
     }
  }
}
}