1. The problem statement, all variables and given/known data arcsec([2 * sqrt(3)] / 3) 2. Relevant equations N/A 3. The attempt at a solution I know that this is equivalent to saying sec (theta) = [2 * sqrt(3)] / 3 I don't know how to solve for theta in terms of PI. I know sec = hyp/adj and the opp side I found was sqrt(3). When I try to do this in the calculator I get a DOMAIN error, and even if I did get an angle it would not be a whole number, how to I convert this in terms of PI?