用vb编程的计算器怎么样编写正弦和余弦函数

一般都是用角度值求三角函数，需要把角度值换算成弧度值。代码如下：
Dim a
Dim pin As Double

Private Sub Form_Load()
pin = 3.14159265358979
End Sub

Private Sub Command1_Click() '求sin按键
a = Sin((Tex_in) * 2 * pin / 360)
Tex_out = a
End Sub

Private Sub Command2_Click() ' 求cos按键
a = Cos((Tex_in) * 2 * pin / 360)
Tex_out = a
End Sub

vb的正余弦函数接受的参数是弧度，得先将传来的角度值转换为弧度值再调用