System.Math.Cos Method

The cosine of

d. Ifdis equal to double.NaN, double.NegativeInfinity, or double.PositiveInfinity, this method returns double.NaN.

The angle, *d*, must be in radians. Multiply by Math.PI/180 to convert degrees to radians.

Acceptable values of *d* range from approximately -9223372036854775295 to approximately 9223372036854775295. For values outside this range, the Math.Cos(double) method returns *d* unchanged rather than throwing an exception.