TAN()
 Computes the tangent of a radian value
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 Syntax

     TAN(<nArc>) --> nTangent

 Argument

     <nArc>  Designates the radian value to determine as a tangent.

 Returns

     TAN() returns the tangent for the <nArc> specified value.

 Description

     TAN() determines the tangent of a value specified in radians.

 Note

     .  If you want to represent the value in degrees, convert it with
        the DTOR() function.

 Example

     Some tangent calculations:

     ? STR(TAN(0), 18, 15)            //  1.000000000000000
     ? STR(TAN(PI() /4), 18, 15)      //  1.000000000000000
     ? STR(TAN(PI() /9), 18, 15)      //  0.363970234266202