Cot-func
The cot(x) function returns value of cotangent for each value of the given x. This and other trigonometric functions can take values in radians, degrees, and gradian. The units are determined by the system.math.angularunits object property (which can also be set in the Options dialog box).
double cot(double x)
x
Returns the cotangent of x.
aa = cot(10); aa = ; //should return 1.5423510453569
Sin, Cos, Tan, Secant, Csc