Question

VB里面怎么求反余弦？还有求出来的余弦角度（不是弧度，是角度）怎么四舍五入？急急！！！

Answer 1

反余弦是没有直接的函数，不过自己可以写在模块里面，也可以直接运算；VB中计算公式
反正弦 Arcsin(X) = Atn(X / Sqr(-X * X + 1))
反余弦Arccos(X) = Atn(-X / Sqr(-X * X + 1)) + 2 * Atn(1)
反正割 Arcsec(X) = Atn(X / Sqr(X * X - 1)) + Sgn((X) - 1) * (2 * Atn(1))
反余割 Arccosec(X) = Atn(X / Sqr(X * X - 1)) + (Sgn(X) - 1) * (2 * Atn(1))
反余切Arccotan(X) = Atn(X) + 2 * Atn(1)

四舍五入用Format函数就好了；比如：
MyStr = Format(334。9, "###0。00") ' 返回 "334.90

Answer 2

代码： Private Sub Command1_Click()
Dim a As Double, b As Double
a = Val(InputBox("请输入一个余弦值:"))
b = Int(ArcCos(a))
MsgBox ("对应的余弦的角度是:" + Str(b))
End SubFunction ArcCos(x As Double) As Double
If x >= -1 And x < -0.5 Then ArcCos = Atn(Sqr(1 - x * x) / x) + 4 * Atn(1)
If x >= -0.5 And x <= 0.5 Then ArcCos = -Atn(x / Sqr(1 - x * x)) + 2 * Atn(1)
If x > 0.5 And x <= 1 Then ArcCos = Atn(Sqr(1 - x * x) / x)
ArcCos = ArcCos / 3.1415926 * 180
End Function
图：