For a glass (n=1.5)/quarts (n=1.38) interface and an angle of incidence of 35 degrees, determine the angle of?

refraction. I found the refraction which is 33.57 degrees, but I am having trouble finding the critical angle for fiber. the equation is sin ^-1 1 n2/n1 and the acceptance angle equation is sin ^-1 radical n^2 1- n^2 2. CAN SOMEONE PLEASE HELP ME!!!!