Cosh
Function 
Cosh(angle)

Cosh is included by default in each file as part of the Math library.
See also:
Use
The Cosh() function returns the hyperbolic cosine of an angle. The input must have an angular unit, but unitless is acceptable and will be treated as radians.
Cosh() also works with complex numbers.
Examples of hyperbolic trig functions
Sinh(pi/4) = 0.869
Sinh(1 rad) = 1.175
Cosh(30 deg) = 1.140
Tanh((30 + 45i) deg) = 0.781 + 0.625i