# Complex.Acos(Complex)Complex.Acos(Complex)Complex.Acos(Complex)Complex.Acos(Complex) Method

## 定義

``````public:
static System::Numerics::Complex Acos(System::Numerics::Complex value);``````
``public static System.Numerics.Complex Acos (System.Numerics.Complex value);``
``static member Acos : System.Numerics.Complex -> System.Numerics.Complex``
``Public Shared Function Acos (value As Complex) As Complex``

#### パラメーター

value
Complex Complex Complex Complex

コサインを表す複素数。A complex number that represents a cosine.

#### 戻り値

`value` のアーク コサインであるラジアン単位の角度。The angle, measured in radians, which is the arc cosine of `value`.

## 例

``````using System;
using System.Numerics;

public class Example
{
public static void Main()
{
Complex[] values = { new Complex(.5, 2),
new Complex(.5, -2),
new Complex(-.5, 2),
new Complex(-.3, -.8) };
foreach (Complex value in values)
Console.WriteLine("Cos(ACos({0})) = {1}", value,
Complex.Cos(Complex.Acos(value)));
}
}
// The example displays the following output:
//       Cos(ACos((0.5, 2))) = (0.5, 2)
//       Cos(ACos((0.5, -2))) = (0.5, -2)
//       Cos(ACos((-0.5, 2))) = (-0.5, 2)
//       Cos(ACos((-0.3, -0.8))) = (-0.3, -0.8)
``````
``````Imports System.Numerics

Module Example
Public Sub Main()
Dim values() As Complex = { New Complex(.5, 2),
New Complex(.5, -2),
New Complex(-.5, 2),
New Complex(-.3, -.8) }
For Each value As Complex In values
Console.WriteLine("Cos(ACos({0})) = {1}", value,
Complex.Cos(Complex.Acos(value)))
Next
End Sub
End Module
' The example displays the following output:
'       Cos(ACos((0.5, 2))) = (0.5, 2)
'       Cos(ACos((0.5, -2))) = (0.5, -2)
'       Cos(ACos((-0.5, 2))) = (-0.5, 2)
'       Cos(ACos((-0.3, -0.8))) = (-0.3, -0.8)
``````

## 注釈

Acos複素数のメソッドに対応して、Math.Acos実数のメソッド。The Acos method for complex numbers corresponds to the Math.Acos method for real numbers.

Acosメソッドは、次の式を使用します。The Acos method uses the following formula:

(-ImaginaryOne) * Log(`value` + ImaginaryOne*Sqrt(One - `value` * `value`)))(-ImaginaryOne) * Log(`value` + ImaginaryOne*Sqrt(One - `value` * `value`)))