Problem calling math.cos()

[Sambo]

I have the following module:
-------------------------------
import math

def ac_add_a_ph( amp1, ph1, amp2, ph2 ):

    amp3 = 0.0 
    ph3 = 0.0
    ac1 = ( 0, 0j )
    ac2 = ( 0, 0j )                                                      
    ac3 = ( 0, 0j )
    ac1 = complex( amp1 * math.cos( math.radians( ph1 ) ), amp1 * math.sin( math.radians( ph1 ) ) )
    ac2 = complex( amp2 * math.cos( math.radians( ph2 ) ), amp2 * math.sin( math.radians( ph2 ) ) )
    ac3 = ac1 + ac2
    amp3 = math.abs( ac3 )
    ph3 = math.atan( ac3.imag / ac3.real )
    return [amp3, ph3]                  
--------------------------------------
when I import it (electronics) in python.exe in windows2000 and 
try to use it, it croaks.  ??? 

>>> import math
>>> import electronics
>>> print electronics.ac_add_a_ph( 10, 0 , 6 , 45 )
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "f:\devel\python\electronics.py", line 10, in ac_add_a_ph
    ac1 = complex( amp1 * math.cos( math.radians( ph1 ) ), amp1 * math.sin( math
.radians( ph1 ) ) )
NameError: global name 'cos' is not defined
>>>


global?? huh?
what does abs stand for? why is that not absolute value? hmmm.
Hmm, complex numbers, cool I don't even have any idea where C 
stands on this.