Am I cooked

I was doing integral of 1/root(16-x^2)) on a test and I got it down into (1/root(1-u^2)) form and I was pretty sure it was just arcsin(u) but I want fully confident so I whipped out trig to do it, but I accidentally showed the trig sub on the actual question, not my scrap paper so I used untaught stuff on the test. Note I did get to the standard arcsin form using u sub and at that point I think I was just allowed to slap down arcsin but still