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Excel TAN Function

Excel TAN function
Summary 

The Excel TAN function returns the tangent of angle given in radians. To supply an angle to TAN in degrees, multiply the angle by PI()/180 or use the RADIANS function to convert to radians.

Purpose 
Get the tangent of an angle
Return value 
The tangent value.
Syntax 
=TAN (number)
Arguments 
  • number - The angle in radians for which you want the tangent.
Version 
Usage notes 

The TAN function returns the tangent of an angle provided in radians. In geometric terms, the tangent of an angle returns the ratio of a right-triangle's opposite side over its adjacent side. For example, the the tangent of PI()/4 (45°) returns the ratio of 1.0.

=TAN(PI()/4) // Returns 1.0

Using Degrees

To supply an angle to TAN in degrees, multiply the angle by PI()/180 or use the RADIANS function to convert to radians. For example, to get the TAN of 60 degrees, you can use either formula below:

=TAN(60*PI()/180)
=TAN(RADIANS(60))

Explanation

Graph of Tangent Function

The graph of the tangent function, shown above, visualizes the output of the function for angles from 0 to a full rotation corresponding to the range [0, 2π]. The function has two vertical asymptotes within the range  [0, 2π] where the output diverges to infinity. The tangent function can be equivalently defined in terms of SIN and COS:

=TAN(θ) = SIN(θ)/COS(θ)

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