Hi, I am can't solve the same problem!
I did the same thing, wrote down the equation for position using unit vectors, then replaced T in Y position equation.
and simplified everything to
Y(t)= -1.4= Vo*sin(alpha)* (1.8/(cos(alpha)*Vo)-.5*32.1*(1.8/(cos(alpha)*Vo))^2
Y(t)= -1.4=...