public class Main {

  public static void main(String[] args) {

    System.out.println(Math.cos(3));

    System.out.println(Math.cos(-3));

    System.out.println(Math.cos(0));

    System.out.println(Math.cos(Math.PI));

    System.out.println(Math.cos(Math.PI/2));

  }

}

​