# What is the value of cos^-1(cos12^o)-sin^-1(sin12^o) ?

0 or 2 pi and multiples since the inverse cosine is the angle. The angle whose cosine is cosine of 12 degrees is the angle itself, that is 12 degrees. Now it could also be 12 degrees plus $2 \pi$, which might be the trick part of the question, if there is one :)