"Who of you" vs "which of you"

"Who" is a pronoun that can exactly mean "which."

Both of your sentences are equally correct. Both are common. Neither is preferable to the other.

Simpler is best. "Who knows what the obliqueness..." is the simplest way to get your point across, and therefore preferable.

Alternatively I might say "Who here knows what the obliqueness..." or "Do any of you know what the obliqueness..." The best option of all may be "Who can explain what the obliqueness..." as it seems likely that you actually want to know whether or not any of your students can explain the concept to the class. If that is indeed what you really want to know, then it's best to ask that question.

I would not use which in this situation because it doesn't sound right to me. I have used this internalized system derived from years and years of reading many books in English, and it has served me very well on standardized tests as well as in the real world. I'm from the South in case some sort of regional variation is at play here.

I think who is preferable because there's a distinct possibility that no one is going to be able to answer the question. As a parent at home alone with two kids you would ask them "Which one of you turned on the microwave with nothing inside?" You KNOW it was one of them. "Who turned on the microwave..." isn't wrong, but it implies that you have no idea who did it as opposed to knowing that it was one of two options.

For what it's worth, I'd say

Which of you know ...

or

Which one of you knows ...

or

Does any one of you know ...

or

Does anyone here know ...

Suggested by @Chase Sandmann (indeed, this one is the most natural-sounding of the group):

Do any of you know ...

"Who of you" sounds awkward.