# Math.Atan2 Method

**Visual Studio 2010**

Returns the angle whose tangent is the quotient of two specified numbers.

**Namespace:**System

**Assembly:**mscorlib (in mscorlib.dll)

#### Parameters

- y
- Type: System.Double

The y coordinate of a point.

- x
- Type: System.Double

The x coordinate of a point.

#### Return Value

Type: System.DoubleFor (x, y) in quadrant 1, 0 < θ < π/2.

For (x, y) in quadrant 2, π/2 < θ ≤ π.

For (x, y) in quadrant 3, -π < θ < -π/2.

For (x, y) in quadrant 4, -π/2 < θ < 0.

If y is 0 and x is not negative, θ = 0.

If y is 0 and x is negative, θ = π.

If y is positive and x is 0, θ = π/2.

If y is negative and x is 0, θ = -π/2.

The following example demonstrates how to calculate the arctangent of an angle and a vector. The resulting value is displayed in 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. '

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.