All of these are from Math, so what they do should be clear:

Name(parameter type) returns (result type)

Sqrt(double) returns double
Exp (double) returns double
Sin (double) returns double
Log (double) returns double
Abs (int/double/float) returns same as parameter type
Pow ( double, double ) double

Example: Sqrt takes as a parameter double and returns result of type double too.
Consider the following links:
a) Example Uses
b) Example Program2
or
r) or back to What do you need to know?
x) or out to Math Funcions