1. Create a new class named MethodComposition and add a method named calculateArea and a method named distance.

public class MethodComposition {
  public static double calculateArea(double radius){
    double result = Math.PI * radius * radius;
    return result;
  }
  public static double distance(double x1, double y1, double x2, double y2){
    double dx = x2-x1;
    double dy = y2-y1;
    double dsquared = dx * dx + dy * dy;
    double result = Math.sqrt(dsquared);
    return result;
  }
}

2. Add a method named circleArea.

public static double circleArea(double xc, double yc, double xp, double yp){
  double radius = distance(xc,yc,xp,yp);
  double area = calculateArea(radius);
  return area;
}

3. Add a main method and have it call circleArea.

public static void main(String[] args){
  double theArea = MethodComposition.circleArea(2.3,9.5,9.8,88.54);
  System.out.println(theArea);
}

The complete class should match the following.

public class MethodComposition {
  public static double calculateArea(double radius){
    double result = Math.PI * radius * radius;
    return result;
  }
  public static double circleArea(double xc, double yc, double xp, double yp){
    double radius = distance(xc,yc,xp,yp);
    double area = calculateArea(radius);
    return area;
  }
  public static void main(String[] args){
    double theArea = MethodComposition.circleArea(2.3,9.5,9.8,88.54);
    System.out.println(theArea);
  }
}

4. Compile the program and run it.

$ javac MethodComposition.java
$ java MethodComposition
19803.25422993726