Generar un condicionamiento IF-Else para realizar suma, resta, multiplicacion y division en un formulario con clicks

private void button1_Click(object sender, EventArgs e)
        {
            if (radioButton1.Checked)
            {
                int a, b, c;
                a = Convert.ToInt32(textBox1.Text);
                b = Convert.ToInt32(textBox2.Text);
                c = a + b;
                textBox3.Text = Convert.ToString(c);
            }
            else if (radioButton2.Checked)
            {
                int a, b, c;
                a = Convert.ToInt32(textBox1.Text);
                b = Convert.ToInt32(textBox2.Text);
                c = a - b;
                textBox3.Text = Convert.ToString(c);
            }
            else if (radioButton3.Checked)
            {
                int a, b, c;
                a = Convert.ToInt32(textBox1.Text);
                b = Convert.ToInt32(textBox2.Text);
                c = a * b;
                textBox