# Tan Function

Determines the tangent of an angle. The angle is specified in radians.

Using the angle Alpha, the Tan function calculates the ratio of the length of the side opposite the angle to the length of the side adjacent to the angle in a right-angled triangle.

Tan(Alpha) = side opposite the angle/side adjacent to angle

### Syntax:

``````
Tan (Number As Double) As Double
``````

Double

### Parameters:

Number: A numeric expression that specifies an angle in radians for which you want to calculate the tangent.

To convert degrees to radians, multiply by Pi/180. To convert radians to degrees, multiply by 180/Pi.

Pi is approximately 3.141593.

### Error codes:

5 Invalid procedure call

### Example:

``````
' In this example, the following entry is possible for a right-angled triangle:
' The side opposite the angle and the angle (in degrees) to calculate the length of the side adjacent to the angle:
Sub ExampleTangens
' Pi = 3.1415926... is a predefined variable
Dim d1 As Double
Dim dAlpha As Double
d1 = InputBox("Enter the length of the side opposite the angle: ","opposite")
dAlpha = InputBox("Enter the Alpha angle (in degrees): ","Alpha")
Print "the length of the side adjacent the angle is"; (d1 / tan (dAlpha * Pi / 180))
End Sub
``````