private void button31_Click(object sender, EventArgs e) { String str = "Radians"; if (Radians.Checked) { str = "Radians"; } else if (Grads.Checked) { str = "Grads"; } else if (Degrees.Checked) { str = "Degrees"; } calculadora.calcular_tangente(str); textBox1.Text = calculadora.stream.textBox; }