COS()
 Computes the cosine
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 Syntax

     COS(<nArc>) --> nCosine

 Argument

     <nArc>  Designates a radian value for which the cosine is
     determined.

 Returns

     COS() returns the cosine value specified in <nArc>.

 Description

     COS() computes the angle cosine measured in radians.

 Note

     .  If you want the values specified in degrees, you can convert
        them with the DTOR() function.

 Example

     Compute the cosine:

     ? STR(COS(0), 18, 15)               // 1.000000000000000
     ? STR(COS(PI() /4), 18, 15)         // 0.707106781186548
     ? STR(COS(PI() /2), 18, 15)         // 0.000000000000000
     ? STR(COS(PI() *99.5), 18, 15)      // 0.000000000000000
     ? STR(COS(PI() /9), 18, 15)         // 0.939692620785908