C sharp programming AT 1.4

// 
// 
// 11/10/2017
// AT1.4

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;

namespace AT1._4
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            // get input from the Form and
            // then parse as integers.
            // CAUTION no error trapping
            int one = int.Parse(tbInputOne.Text);
            int two = int.Parse(tbInputTwo.Text);
            clearOutput();
            runCal(one, two);
        }
        private void clearOutput()
        {
            // clear the output text boxes
            tbOneA.Clear();
            tbOneB.Clear();
            tbTwoA.Clear();
            tbTwoB.Clear();
            tbThreeA.Clear();
            tbThreeB.Clear();
            tbFinalA.Clear();
            tbFinalB.Clear();
        }
        private void runCal(int a, int b)
        {
            // IF statement number One
            if (a > b)
            {
                int temp = b;
                b = a;
                a = temp;
                tbOneA.Text = a.ToString();
                tbOneB.Text = b.ToString();
            }
            // IF statement number two
            if ((Math.Cos(a)) < 0 && (Math.Cos(b) > 0))
            {
                a = 1;
                b = 3;
                tbTwoA.Text = a.ToString();
                tbTwoB.Text = b.ToString();
            }
            int x = (a + b) / 2;
            // IF statement number three
            if (Math.Cos(x) > 0)
            {
                a = x;
                tbThreeA.Text = a.ToString();
            }
            else
            {
                b = x;
                tbThreeB.Text = b.ToString();
            }
            // Final values of a and b
            tbFinalA.Text = a.ToString();
            tbFinalB.Text = b.ToString();
        }
    }
}


/* Step One
    Input / Expected Output / Actual Results
    5,2 / 1,2 / 1,2
    8,6 / 7,8 / 7,8
    2,5 / 1,2 / 1,2
    4,4 / 4,4 / 1,2
    7,5 / 6,7 / 1,2
    4,8 / 6,8 / 1,2
    9,7 / 7,8 / 7,8
 */

/*
    Change line 54
    if ((Math.Cos(a)) < 0 || (Math.Cos(b) > 0))
    to
    if ((Math.Cos(a)) < 0 && (Math.Cos(b) > 0))
*/

/*
     in Cos(x), when x is 1, 5, 6 or 7, it's value is positive (cos(x)>0)
     when x is 2, 3, 4, 8, 9 or 10, it's value is nagative (cos(x)<0)

    5,2 / 2,5 / -, + only thing that has to work second if statement
    8,6 / 6,8 / +, -
    2,5 / 2,5 / -, +
    4,4 / 4,4 / -, -
    7,5 / 5,7 / +, +
    4,8 / 4,8 / -, -
    9,7 / 7,9 / +, -
 */

idle / input 7, 5 / input 5, 2