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I am having problem with calculating the angle using sin. So far, I got the literal of numbers, which is not making sense.
I am supposed to match my answers with this:

Set up new triangle with coordinates (0.0, 0.0), (3.0, 0.0), (3.0, 4.0)
Area: 6.0
Parimeter: 12.0
Length side a: 4.0
Length side b: 5.0
Length side c: 3.0
Angle A: 53.13010235415598
Angle B: 90.0
Angle C: 36.86989764584402
Height: 4.0

But I got this:

Set up new triangle with coordinates (0.0,0.0), {3.0,0.0), (3.0,4.0)
Area: 6.0
Parameter: 12.0
Length side a: 4.0
Length side b: 5.0
Length side c: 3.0
Angle A: 0.9272952180016123
Angle B: 1.5707963267948966
Angle C: 0.6435011087932843
Height: 4.0


Where do I go wrong?

Test Class

import javax.swing.JOptionPane;

public class TriangleTester
{
    public static void main(String args[])
    {
        /*Initializes the variables.
           Getting the coordinates from the user
          */
        double xPointA =  Double.parseDouble(JOptionPane.showInputDialog("Enter x1 for point A:"));
        double yPointAB = Double.parseDouble(JOptionPane.showInputDialog("Enter y1 for point A and B:"));
        double x2PointB = Double.parseDouble(JOptionPane.showInputDialog("Enter x2 for point B:"));
        double x3PointC = Double.parseDouble(JOptionPane.showInputDialog("Enter x3 for point C:"));
        double y2PointC = Double.parseDouble(JOptionPane.showInputDialog("Enter y2 for point C:"));
           
          //Creating an object
           Triangle math = new Triangle();
          
          math.calcLength(xPointA,yPointAB,x2PointB,yPointAB,x3PointC,y2PointC);
          math.calcParameter();
          math.calcArea(y2PointC);
          

          System.out.println("Set up new triangle with coordinates (" + xPointA + "," + yPointAB + "), {" 
                                      + x2PointB + "," + yPointAB + "), (" + x3PointC + "," + y2PointC + ")");
          
          System.out.println("Area: " + math.getArea());
          System.out.println("Parameter: " + math.getParimeter());
          System.out.println("Length side a: " + math.getLengthA());
           System.out.println("Length side b: " + math.getLengthB());
           System.out.println("Length side c: " + math.getLengthC());
          System.out.println("Angle A: " + math.getAngleA());
          System.out.println("Angle B: " + math.getAngleB());
          System.out.println("Angle C: " + math.getAngleC());
          System.out.print("Height: " + y2PointC);
     }
}

Functional Class

import java.lang.Math;

public class Triangle
{
    //Insti
    double area;
    double lengthA;
    double lengthB;
    double lengthC;
    double angleA;
    double angleB;
    double angleC;
    double paraNum;        
    
    public void calcLength(double Ax, double Ay, double Bx, double By, double Cx, double Cy)
    {
        
        lengthA = (Math.pow((Cx - Bx),2) + Math.pow((Cy -By), 2));
        lengthA = Math.sqrt(lengthA);
        
        lengthB = (Math.pow((Cx - Ax),2) + Math.pow((Cy -Ay), 2));
        lengthB = Math.sqrt(lengthB);

        lengthC = (Math.pow((Bx - Ax),2) + Math.pow((By -Ay), 2));
        lengthC = Math.sqrt(lengthC);                
   }
    
    //Calculate the area with the parameter of height.
    public void calcArea(double height)
    {
        area = (lengthC * height);
        area = area / 2;
    }
    
    
    public void calcParameter()
    {
        paraNum = lengthA + lengthB + lengthC;
    }
        
    
    public double getParimeter()
    {
        return paraNum;
    }
        
    public double getLengthA()
    {
        return lengthA;
    }
    
    public double getLengthB()
    {
        return lengthB;
    }

    public double getLengthC()
    {
        return lengthC;
    }        
    
    
    public double getAngleA()
    {
        angleA = Math.acos((lengthB*lengthB + lengthC*lengthC - lengthA*lengthA) / (2*lengthB*lengthC));
        return angleA;
    }
    
    public double getAngleB()
    {
        angleB = Math.acos((lengthA*lengthA + lengthC*lengthC - lengthB*lengthB) / (2*lengthA*lengthC));
        return angleB;
    }

    public double getAngleC()
    {
        angleC = Math.acos((lengthB*lengthB + lengthA*lengthA - lengthC*lengthC) / (2*lengthB*lengthA));
        return angleC;
    }    
    
    
    public double getArea()
    {
        return area;
    }    
}
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Last Post by tong1
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As indicated by API :
acos
public static double acos(double a)Returns the arc cosine of a value; the returned angle is in the range 0.0 through pi.
The return value of Math.acos is in radian instead of degree. It has to be multiplied by 57.296 (180/PI) to become the value in degree.

Edited by tong1: n/a

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