Learning Python : >>> import math doesn't work ?

[pdlemper at earthlink.net]

Have carefully installed Python 2.5.1 under XP in dir E:\python25 .
ran   set path = %path% ; E:\python25
Python interactive mode works fine for simple arithmetic .
Then tried >>>  import math
                >>>  x = sqrt(100)
   Get error    Name error : name 'sqrt' is not defined
        Same thing with sin(x) .
I'm unable to find "math" , "sqrt" , or "sin" anywhere in lib , Libs
or include directories .
The Tutorial does not clear this up .
Please help.    Thanks  Dave     pdlemper at earthlink.net