Sqrt
Function 
Sqrt(value)

Sqrt is included by default in each file as part of the Math library.
See also:
Use
The Sqrt() function returns the square root of a given number. It works with units and complex numbers.
In dynamic equations, the Sqrt() function appears as the radical sign.
Examples
Sqrt(4) = 2
Sqrt(4 ft^2) = 2ft
Sqrt(4) = 2i
Sqrt(4 + 16i) = 3.2 + 2.5i