Laba7/Form1_Lab3.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using static System.Windows.Forms.VisualStyles.VisualStyleElement;

namespace Ul_3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            double x = double.Parse(textBox1.Text);
            double y = double.Parse(textBox2.Text);

            // решаем уравнение
            double result = SolveEquation(x, y);

            // выводим результат
            textBox3.Text = result.ToString();
        }

        private double SolveEquation(double x, double y)
        {
            double result = 0;

            if (Math.Abs(x - y) < 0.0001)
            {
                result = Math.Pow(Math.Sin(x), 2) + Math.Sin(y);
            }
            else if (x - y > 0)
            {
                result = Math.Cos(x) + Math.Cos(y);
            }
            else if (x - y < 0)
            {
                result = y - Math.Pow(Math.Tan(x), 2) + Math.Tan(y);
            }

            return result;
        }
    }
}