The FoV settings in BFBC2 are really wierd. They are not horizontal like most games. Instead, its vertical. Who the heck came up with that system is beyond me. Luckily, someone already did the math for us.
http://rjdown.co.uk/projects/bfbc2/fovcalculator.php
http://rjdown.co.uk/projects/bfbc2/fovcalculator.php