Hey guys, The problem is #49 and it is a simple calculus problem, but the part that I am confused on is how the solution solves the trig. equation. In the solving, the solution brings out the plus-minus symbol and puts it outside the arccos, but I feel as if it should be inside the arccos. I understand that putting the symbol outside solves the problem perfectly, but it seems like a shortcut. How I think it should be done is to put the plus-minus symbol inside the arcccos (it would give us two different answers) and choose the answer that fits into the domain of the problem which is (pi/4 and -pi/4). When I choose the answer that fits into the domain, I can make it positive or negative because the secant is squared. Thanks!