有几个地方要注意：
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1、VB中的三角函数的角度全部是用弧度制表示的，如果是度数的话，应先乘以180再除以π转成弧度，再用函数计算结果。
2、VB中直接支持的三角函数有：Sin()、Cos()、Tan()，如果涉及到其它三角函数，可以从下面列出的代码中自己选择相应的函数：
Function
Sec(X)
As
Double
'正割
Sec
=
1
/
Cos(Angle)
End
Function
Function
Csc(X)
As
Double
'余割
Csc
=
1
/
Sin(Angle)
End
Function
Function
Cot(X)
As
Double
'余切
Cot
=
1
/
Tan(Angle)
End
Function
Function
ArcSin(X)
As
Double
'反正弦
ArcSin
=
Atn(X
/
Sqr(-X
*
X
+
1))
End
Function
Function
ArcCos(X)
As
Double
'反余弦
ArcCos
=
Atn(-X
/
Sqr(-X
*
X
+
1))
+
2
*
Atn(1)
End
Function
Function
ArcSec(X)
As
Double
'反正割
ArcSec
=
Atn(X
/
Sqr(X
*
X
-
1))
+
Sgn((X)
-
1)
*
(2
*
Atn(1))
End
Function
Function
ArcCsc(X)
As
Double
'反余割
ArcCsc
=
Atn(X
/
Sqr(X
*
X
-
1))
+
(Sgn(X)
-
1)
*
(2
*
Atn(1))
End
Function
Function
ArcCot(X)
As
Double
'反余切
ArcCot
=
Atn(X)
+
2
*
Atn(1)
End
Function
Function
HSin(X)
As
Double
'双曲正弦
HSin
=
(Exp(X)
-
Exp(-X))
/
2
End
Function
Function
HCos(X)
As
Double
'双曲余弦
HCos
=
(Exp(X)
+
Exp(-X))
/
2
End
Function
Function
HTan(X)
As
Double
'双曲正切
HTan
=
(Exp(X)
-
Exp(-X))
/
(Exp(X)
+
Exp(-X))
End
Function
Function
HSec(X)
As
Double
'双曲正割
HSec
=
2
/
(Exp(X)
+
Exp(-X))
End
Function
Function
HCsc(X)
As
Double
'双曲余割
HCsc
=
2
/
(Exp(X)
-
Exp(-X))
End
Function
Function
HCot(X)
As
Double
'双曲余切
HCot
=
(Exp(X)
+
Exp(-X))
/
(Exp(X)
-
Exp(-X))
End
Function
Function
HArcsin(X)
As
Double
'反双曲正弦
HArcsin
=
Log(X
+
Sqr(X
*
X
+
1))
End
Function
Function
HArccos(X)
As
Double
'反双曲余弦
HArccos
=
Log(X
+
Sqr(X
*
X
-
1))
End
Function
Function
HArctan(X)
As
Double
'反双曲正切
HArctan
=
Log((1
+
X)
/
(1
-
X))
/
2
End
Function
Function
HArcsec(X)
As
Double
'反双曲正割
HArcsec
=
Log((Sqr(-X
*
X
+
1)
+
1)
/
X)
End
Function
Function
HArccsc(X)
As
Double
'反双曲余割
HArccsc
=
Log((Sgn(X)
*
Sqr(X
*
X
+
1)
+
1)
/
X)
End
Function
Function
HArccot(X)
As
Double
'反双曲余切
HArccot
=
Log((X
+
1)
/
(X
-
1))
/
2
End
Function
Dim Points1(30) As Point
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Timer1.Enabled = True
Timer1.Interval = 200
For i = 0 To 30
Points1(i) = New Point(i * 45, Math.Sin(i) * (PictureBox1.Height - 50) / 9)
Points1(i).Offset(-450, Math.Abs(Points1(i).Y - (PictureBox1.Height - 50) / 9) * 3.55 + 43)
Next
End Sub
Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick
Static j As Long
j = j + 1
PictureBox1.Image = x_y(PictureBox1, j)
End Sub
Private Function x_y(ByVal pic As PictureBox, ByVal x As Long) As Bitmap
Dim b As New Bitmap(pic.Width, pic.Height)
Dim g As Graphics = Graphics.FromImage(b)
Dim c
Dim j
g.Clear(Color.YellowGreen)
Dim p As New Pen(Color.WhiteSmoke)
p.EndCap = Drawing2D.LineCap.ArrowAnchor
g.DrawLine(p, 20, pic.Height - 20, 20, 10)
g.DrawLine(p, 20, pic.Height - 20, pic.Width - 20, pic.Height - 20)
Dim i As Double
Dim bs As New SolidBrush(Color.Red)
Dim po As New Point
g.DrawString(-2, Me.Font, bs, 12, pic.Height - 18)
po.X = 0
po.Y = pic.Height - 45
For i = -1.6 To 4 Step 0.4
g.DrawString(Math.Round(i, 1), Me.Font, bs, po.X, po.Y)
g.DrawLine(p, po.X + 18, po.Y + 5, po.X + 20, po.Y + 5)
Dim p1 As New Pen(Color.Blue)
p1.DashStyle = Drawing2D.DashStyle.Dash
g.DrawLine(p1, po.X + 28, po.Y + 5, pic.Width - 20, po.Y + 5)
po.Y -= (pic.Height - 50) / 9
Next
po.X = 20
po.Y = pic.Height - 20
For c = 0 To 14400 Step 1200
If (c / 1200) 0 Then
g.DrawString((c / 1200) + x, Me.Font, bs, po.X - j, po.Y + 5)
End If
g.DrawLine(p, po.X, po.Y + 2, po.X, po.Y)
po.X += (pic.Width - 50) / 12
Next
For i = 0 To Points1.Count - 1
Points1(i).Offset(45, 0)
Next
If x Mod 6 = 0 Then
For i = 0 To Points1.Count - 1
Points1(i).Offset(-270, 0)
Next
End If
g.DrawCurve(Pens.Red, Points1)
'For i = 0 To Points1.Count - 1
'g.DrawString(Math.Sin(i), Me.Font, Brushes.Red, Points1(i))
'Next
Return b
End Function
Cos(pi * C * 6 / 180) 中的 pi是π值，C 是变量，pi * C * 6 / 180 计算出的是弧度数。
Sin(pi * C * 6 / 180) 同上。
Sin(mm) 中的 mm 可以是任何有理数（正无穷大到负无穷大），即可以是一个正的有理数，也可以是一个负的有理数，同样也可以是0，在VB计算时程序就认为 mm 是弧度数，故此，只要 mm 是有理数，那么就可以的。
如果 mm 是角度数，必须转换为弧度数。
为什么我的不是?
Dim pi
pi = 3.1415926
Dim a
a = 30
Text1.Text = Sin(a * pi / 180)
