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

Function Description

The Excel TAN function calculates the tangent of a given angle.

The syntax 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 Tan function.

This can be done by using the Excel Radians function:

=RADIANS( degrees )
An example of this is given below.

Tan Function Examples

The following spreadsheet shows the Excel Tan Function, used to calculate the tangent of four different angles.

  A B
1 =TAN( 1.047197551 )  - tan of 1.047197551 Radians
2 =TAN( 0 )  - tan of 0 Radians
3 =TAN( PI()/4 )  - tan of π/4 Radians
4 =TAN( RADIANS( -45 ) )  - tan of -45 Degrees
1 1.732050807
2 0
3 1
4 -1

Note that in the above examples:

For further information and examples of the Excel Tan function, see the Microsoft Office website.