The Excel TAN Function

Related Functions:
COS Function
SIN Function

Tangent of an Angle

For the simple right-angled triangle below, the tangent of the angle θ, is the ratio of the opposite side, o, to the adjacent side, a.

Right-Angled Triangle

i.e. for the triangle above,

Tangent Equation

The trig. ratios are discussed further on the Wikipedia Trigonometric Ratios Page

Basic Description

The Excel TAN function calculates the tangent of a given angle (which is supplied in radians).

The format of the function is :

TAN( number )

Where the number argument is the angle, in radians, that you want to calculate the tangent of.

Converting from Radians to Degrees

If your angle is in degrees, you will need to convert it into radians before supplying it to the cos function.

The easiest way to do this is to use the Excel Radians function:

=RADIANS( degrees )

Examples of this are given below.

Tan Function Examples

Column B of the spreadsheet below, shows examples of the Excel Tan Function, used to calculate the tangent of different angles, which are in either degrees or radians.

  A B
1 1.047197551 Radians =TAN( 1.047197551 )
2 π/4 Radians =TAN( PI()/4 )
3 45 Degrees =TAN( RADIANS( 45 ) )
4 -45 Degrees =TAN( RADIANS( -45 ) )
  A B
1 1.047197551 Radians 1.732050807
2 π/4 Radians 1
3 45 Degrees 1
4 -45 Degrees -1

Further information and examples of the Excel Tan function can be found on the Microsoft Office website.