Hey guys, I'm making a program that takes 3 sets of coordinates from a user to make a triangle. It then calculates the length of each side, the perimeter of the triangle, the area of the triangle, and the 3 angles. I have it all coded, except for the area and angles, I get a return value of NaN. can anyone explain why this is happening?

```
public class Triangle
{
public Triangle(double x, double y, double xa, double ya, double xb, double yb)
{
x1 = x;
x2 = xa;
x3 = xb;
y1 = y;
y2 = ya;
y3 = yb;
}
private double x1;
private double x2;
private double x3;
private double y1;
private double y2;
private double y3;
private double A;
private double B;
private double C;
private double perimeter;
private double area;
private double angle1;
private double angle2;
private double angle3;
private double S;
public double getSide1()
{
A = Math.sqrt(Math.pow((x1-x2),2)+Math.pow((y1-y2),2));
return A;
}
public double getSide2()
{
double B = Math.sqrt(Math.pow((x2-x3),2)+Math.pow((y2-y3),2));
return B;
}
public double getSide3()
{
double C = Math.sqrt(Math.pow((x3-x1),2)+Math.pow((y3-y1),2));
return C;
}
double AA = Math.pow(A, 2);
double BB = Math.pow(B, 2);
double CC = Math.pow(C, 2);
public double getPerimeter()
{
perimeter = (A + B + C);
return perimeter;
}
public double getS()
{
S = (perimeter * 0.5);
return S;
}
public double getArea()
{
area = (Math.sqrt(S*(S-A)*(S-B)*(S-C)));
return area;
}
public double getAngle1()
{
angle1 = Math.acos((BB + CC - AA)/(2*B*C))*(180/Math.PI); //gets the angle in radians and converts to degrees
return angle1;
}
public double getAngle2()
{
angle2 = Math.acos((AA + CC - BB)/(2*A*C))*(180/Math.PI);
return angle2;
}
public double getAngle3()
{
angle3 = Math.acos((AA + BB - CC)/(2*B*A))*(180/Math.PI);
return angle3;
}
}
```

```
import java.util.Scanner;
public class TriangleSimulator
{
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
System.out.println("Please enter the first x coordinate:");
double x1 = in.nextDouble();
System.out.println("Please enter the first y coordinate:");
double y1 = in.nextDouble();
System.out.println("Please enter the second x coordinate:");
double x2 = in.nextDouble();
System.out.println("Please enter the second y coordinate:");
double y2 = in.nextDouble();
System.out.println("Please enter the third x coordinate:");
double x3 = in.nextDouble();
System.out.println("Please enter the third y coordinate:");
double y3 = in.nextDouble();
Triangle tri = new Triangle(x1, y1, x2, y2, x3, y3);
System.out.println("Side 1 is: " + tri.getSide1());
System.out.println("Side 2 is: " + tri.getSide2());
System.out.println("Side 3 is: " + tri.getSide3());
System.out.println("The perimeter is: " + tri.getPerimeter());
System.out.println("The area is: " + tri.getArea());
System.out.println("Angle 1 is: " + tri.getAngle1());
System.out.println("Angle 2 is: " + tri.getAngle2());
System.out.println("Angle 3 is: " + tri.getAngle3());
}
}
```