# Math.Tan Method (Double)

.NET Framework (current version)

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Returns the tangent of the specified angle.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

## Syntax

```Public Shared Function Tan (
a As Double
) As Double
```

#### Parameters

a
Type: System.Double

An angle, measured in radians.

#### Return Value

Type: System.Double

The tangent of a. If a is equal to NaN, NegativeInfinity, or PositiveInfinity, this method returns NaN.

## Remarks

The angle, a, must be in radians. Multiply by Math.PI/180 to convert degrees to radians.

## Examples

The following example demonstrates how to calculate the tangent of an angle and display it to the console.

```' This example demonstrates Math.Atan()
'                           Math.Atan2()
'                           Math.Tan()
Imports System

Class Sample
Public Shared Sub Main()
Dim x As Double = 1.0
Dim y As Double = 2.0
Dim angle As Double
Dim radians As Double
Dim result As Double

' Calculate the tangent of 30 degrees.
angle = 30
radians = angle *(Math.PI / 180)
result = Math.Tan(radians)
Console.WriteLine("The tangent of 30 degrees is {0}.", result)

' Calculate the arctangent of the previous tangent.
radians = Math.Atan(result)
angle = radians *(180 / Math.PI)
Console.WriteLine("The previous tangent is equivalent to {0} degrees.", angle)

' Calculate the arctangent of an angle.
Dim line1 As [String] = "{0}The arctangent of the angle formed by the x-axis and "
Dim line2 As [String] = "a vector to point ({0},{1}) is {2}, "
Dim line3 As [String] = "which is equivalent to {0} degrees."

radians = Math.Atan2(y, x)
angle = radians *(180 / Math.PI)

Console.WriteLine(line1, Environment.NewLine)
Console.WriteLine(line2, x, y, radians)
Console.WriteLine(line3, angle)
End Sub 'Main
End Class 'Sample
'
'This example produces the following results:
'
'The tangent of 30 degrees is 0.577350269189626.
'The previous tangent is equivalent to 30 degrees.
'
'The arctangent of the angle formed by the x-axis and
'a vector to point (1,2) is 1.10714871779409,
'which is equivalent to 63.434948822922 degrees.
'
```

## Version Information

Universal Windows Platform
Available since 8
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1

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