## C# Math.Cos() – Examples

In this tutorial, we will learn about the C# Math.Cos() method, and learn how to use this method to find the cosine of given angle, with the help of examples.

## Cos(Double)

Math.Cos(a) returns the cosine of the specified angle `a`. Cos() function considers the specified angle in radians.

### Syntax

The syntax of Cos() method is

`Math.Cos(Double a)`

where

Return Value

The method returns double value.

### Example 1 – Cos(45 degrees)

In this example, we will compute cosine for 45 degrees. We know that cos(45 degrees) is inverse of square root 2.

C# Program

```using System;

class Example {
static void Main(string[] args) {
Double angle = Math.PI/4; //45 degrees

Double value = Math.Cos(angle);
Console.WriteLine(\$"Cosine ({(180 / Math.PI) * angle} degrees) = {value}");
}
}```

Output

`Cosine (45 degrees) = 0.707106781186548`

### Example 2 – Cos(90 degrees)

In this example, we will compute cosine for 90 degrees. We know that cos(90 degrees) is 0.

C# Program

```using System;

class Example {
static void Main(string[] args) {
Double angle = Math.PI/2; //90 degrees

Double value = Math.Cos(angle);
Console.WriteLine(\$"Cosine ({(180 / Math.PI) * angle} degrees) = {value}");
}
}```

Output

`Cosine (90 degrees) = 6.12323399573677E-17`

`6.12323399573677E-17` is very very near to zero. This can be considered zero until the precision of 16 digits after decimal.

### Example 3 – Cos(-60 degrees)

In this example, we will compute cosine for -60 degrees. We know that cos(-60 degrees) is 0.5

C# Program

```using System;

class Example {
static void Main(string[] args) {
Double angle = Math.PI/3; //-60 degrees

Double value = Math.Cos(angle);
Console.WriteLine(\$"Cosine ({(180 / Math.PI) * angle} degrees) = {value}");
}
}```

Output

`Cosine (60 degrees) = 0.5`

### Conclusion

In this C# Tutorial, we have learnt the syntax of C# Math.Cos() method, and also learnt how to use this method with the help of C# example programs.