exact value of cos 165

HELP :(

Question

exact value of cos 165

HELP :(

anonymous · Answer

This appears to be just a calculator question... what part is causing you trouble?

anonymous · Answer

I think the answer is (√ 2 - √ 6)/(4) but I'm not sure

anonymous · Answer

It's not a calculator question haha

anonymous · Answer

I see... "EXACT" means not a calculator answer... sorry!  Makes more sense as a question now :)

165 degrees is 15 degrees less than 180 degrees, which is "pi".

anonymous · Answer

ehhh okay well is my answer correct?(:

anonymous · Answer

I'm not sure... still thinking about it.

anonymous · Answer

welp wasn't that never mind now!

anonymous · Answer

How did you come up with  (√ 2 - √ 6)/(4)  ?

anonymous · Answer

It was an answer choice and I already submitted and got it wrong! OH well...

anonymous · Answer

sorry, I wasn't prepared for what this question actually was :(

I think you're supposed to use trig identities to get cos (11/12 pi) (which is 165 degrees) into some more simple form, but I'm not sure... sorry I didn't figure it out in time to help.