# Complex.Cos(Complex) 方法

## 定义

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

value
Complex

#### 返回

`value` 的余弦值。The cosine of `value`.

## 示例

``````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)
``````

## 注解

Cos 方法使用以下公式来计算复数 a + bi 的余弦值：The Cos method uses the following formula to calculate the cosine of the complex number a + bi:

Cos（a） * Cosh（b），-（Sin（a） * Sinh（b）））(Cos(a) * Cosh(b), -(Sin(a) * Sinh(b)))