12, 3

import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;

import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JTextArea;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JScrollPane;

public class Task3 extends JFrame {

    /**
     *
     */
    private static final long serialVersionUID = 1L;
    private JPanel contentPane;
    private JTextField textField;
    private JTextField textField_1;
    private JTextField textField_2;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Task3 frame = new Task3();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public Task3() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 653, 391);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        JMenuBar menuBar = new JMenuBar();
        menuBar.setBounds(0, 0, 435, 21);
        contentPane.add(menuBar);

        JMenu mnNewMenu = new JMenu("\u041E\u0431\u0447\u0438\u0441\u043B\u0435\u043D\u043D\u044F");
        menuBar.add(mnNewMenu);

        JScrollPane scrollPane = new JScrollPane();
        scrollPane.setBounds(10, 32, 371, 314);
        contentPane.add(scrollPane);

        JTextArea textArea = new JTextArea();
        scrollPane.setViewportView(textArea);

        JLabel lblNewLabel = new JLabel("y=3cos x-1");
        lblNewLabel.setBounds(392, 33, 63, 14);
        contentPane.add(lblNewLabel);

        JLabel lblNewLabel_1 = new JLabel("\u043B\u0456\u0432\u0430 \u043C\u0435\u0436\u0430");
        lblNewLabel_1.setBounds(505, 153, 83, 14);
        contentPane.add(lblNewLabel_1);

        JLabel label = new JLabel("\u043F\u0440\u0430\u0432\u0430 \u043C\u0435\u0436\u0430");
        label.setBounds(505, 197, 83, 14);
        contentPane.add(label);

        JLabel label_1 = new JLabel("\u043A\u0440\u043E\u043A");
        label_1.setBounds(505, 240, 83, 14);
        contentPane.add(label_1);

        textField = new JTextField();
        textField.setBounds(502, 173, 86, 20);
        contentPane.add(textField);
        textField.setColumns(10);

        textField_1 = new JTextField();
        textField_1.setColumns(10);
        textField_1.setBounds(501, 214, 86, 20);
        contentPane.add(textField_1);

        textField_2 = new JTextField();
        textField_2.setColumns(10);
        textField_2.setBounds(502, 258, 86, 20);
        contentPane.add(textField_2);

        JMenuItem mntmNewMenuItem = new JMenuItem("\u043F\u0440\u043E\u0442\u0430\u0431\u0443\u043B\u044E\u0432\u0430\u0442\u0438");
        mntmNewMenuItem.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                textArea.setText("x f(x)");

                double a = Double.parseDouble(textField.getText());
                double b = Double.parseDouble(textField_1.getText());
                double h = Double.parseDouble(textField_2.getText());

                int i = 0, count = 0, minElementNumber = 0;

                double x = a, y;
                double[] masiv = new double[(int) ((b - a) / h) + 1];
                double min = 3 * Math.cos(x) - 1;

                while (x <= b) {
                    y = 3 * Math.cos(x) - 1;
                    masiv[i] = y;

                    if (masiv[i] < min) {
                        min = masiv[i];
                        minElementNumber = i + 1;
                    }

                    if (masiv[i] > 0 && i % 2 == 0) {
                        count++;
                    }

                    i++;
                    textArea.append("\n" + x + " " + y + " -" + i + "ий елемент масиву ");
                    x = x + h;
                }
                textArea.append("\nіндекс  мінімального елементу " + minElementNumber);
                textArea.append("\nкількість додатніх елементів, що стоять на парних місцях " + count);
            }
        });
        mnNewMenu.add(mntmNewMenuItem);

        JMenuItem mntmNewMenuItem_1 = new JMenuItem("\u043E\u0447\u0438\u0441\u0442\u0438\u0442\u0438");
        mntmNewMenuItem_1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                textArea.setText("");
            }
        });
        mnNewMenu.add(mntmNewMenuItem_1);

        JMenu menu = new JMenu("\u041A\u0456\u043D\u0435\u0446\u044C");
        menuBar.add(menu);

        JMenuItem mntmNewMenuItem_2 = new JMenuItem("\u043F\u0440\u043E \u043F\u0440\u043E\u0433\u0440\u0430\u043C\u0443");
        mntmNewMenuItem_2.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                JOptionPane.showMessageDialog(null, "Про програму", null, JOptionPane.INFORMATION_MESSAGE);
            }
        });
        menu.add(mntmNewMenuItem_2);

        JMenuItem mntmNewMenuItem_3 = new JMenuItem("\u043F\u0440\u043E \u0430\u0432\u0442\u043E\u0440\u0430");
        mntmNewMenuItem_3.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                JOptionPane.showMessageDialog(null, "Про автора", null, JOptionPane.INFORMATION_MESSAGE);
            }
        });
        menu.add(mntmNewMenuItem_3);

        JMenuItem mntmNewMenuItem_4 = new JMenuItem("\u0432\u0438\u0445\u0456\u0434");
        mntmNewMenuItem_4.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                System.exit(0);
            }
        });
        menu.add(mntmNewMenuItem_4);
    }
}