Pronunciation of 'cos' (as in the mathematical term)

What is the correct pronunciation for the mathematical abbreviation 'cos' when it is not pronounced in its complete form 'cosine'? I pronounce it as 'k-aw-ss', but a couple of Canadian friends I have pronounce it as 'k-oh-s' (like the adjective 'close'). I tried looking up dictionaries but none that I came across list the IPA / phonetic pronunciation for the mathematical abbreviation.

(I think the former is the British English pronunciation, and the latter is the American English / Canadian English pronunciation.)

In England everybody I know pronounces this so that it rhymes with "because".

In speaking, I'd never use either of those pronunciations. "cos" means "cosine" -- say "cosine". Therefore I'd pronounce it "co-sign" ;)