What is wrong with the format changed to others the same error when entering these numbers swears on the 25th line?

Question

C++ / C#

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 WindowsFormsApp2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            {
                double x, y, z, a, b, q;
                 a = Convert.ToDouble(textBox1.Text);
                b = Convert.ToSByte(textBox2.Text);
                q = Convert.ToSByte(textBox3.Text);
                x = Convert.ToSByte(textBox4.Text);
                y = Convert.ToDouble(textBox5.Text);
                
                z =( Math.Sqrt((a + Math.Cos(x) * Math.Log10(q)) / (b + y * Math.Sin(x))));

                listBox1.Items.Add(" При a=" + a);
                listBox1.Items.Add("     b=" + b);
                listBox1.Items.Add("     q=" + q);
                listBox1.Items.Add("     x=" + x);
                listBox1.Items.Add("     y=" + y);
                listBox1.Items.Add("z= " + z);
            }



        }

        private void button2_Click(object sender, EventArgs e)
        
            { Application.Exit();
        }
        }
    }

Answer 1

Cosines and sines expect an argument in radians, and you probably give it degrees.
P.S. Naturally, I did not consider where you have line 25 there, and what kind of mistake you have. But the elixir of telepathy makes itself felt.