Hello. This should be an easy one, but the answer I'm getting doesn't match the answer in my text book, so I just want someone to help me either confirm it as a misprint or show me what I did wrong:

The question is:

Evaluate the following with a calculator, give the answer in degrees rounded to two decimal places:

$\displaystyle cot^{-1}(-4.2319)$

I get: -13.30 degrees

My text book says: 166.70 degrees

Thanks!